U.S. patent application number 09/341181 was filed with the patent office on 2003-01-16 for cellulosic particles, spherical object comprising cross-linked polymer particles, and adsorbent for body fluid purification.
Invention is credited to FUJITA, KOUJI, OKUYAMA, TSUTOMU, TAKATA, SATOSHI, TANAKA, KOUICHIRO.
Application Number | 20030012941 09/341181 |
Document ID | / |
Family ID | 27517979 |
Filed Date | 2003-01-16 |
United States Patent
Application |
20030012941 |
Kind Code |
A1 |
FUJITA, KOUJI ; et
al. |
January 16, 2003 |
CELLULOSIC PARTICLES, SPHERICAL OBJECT COMPRISING CROSS-LINKED
POLYMER PARTICLES, AND ADSORBENT FOR BODY FLUID PURIFICATION
Abstract
The present invention relates to a cellulosic particle body
comprising interconnected cellulosic small particles with small
interparticle spaces and to a method of producing said cellulosic
particle body which comprises dispersing cellulosic small particles
in an alkaline medium and contacting the resulting suspension with
a coagulating solution. In this specification, the above technology
will be referred to as the first invention.
Inventors: |
FUJITA, KOUJI; (IBARAKI-SHI,
JP) ; OKUYAMA, TSUTOMU; (KOBE-SHI, JP) ;
TANAKA, KOUICHIRO; (SETTSU-SHI, JP) ; TAKATA,
SATOSHI; (TAKASAGO-SHI, JP) |
Correspondence
Address: |
BURTON A AMERNICK
POLLOCK VANDE SANDE & AMERNICK
PO BOX 19088
WASHINGTON
DC
200363425
|
Family ID: |
27517979 |
Appl. No.: |
09/341181 |
Filed: |
August 17, 1999 |
PCT Filed: |
January 7, 1998 |
PCT NO: |
PCT/JP98/00015 |
Current U.S.
Class: |
428/304.4 |
Current CPC
Class: |
C08J 2301/02 20130101;
Y10T 428/249986 20150401; Y10T 428/249987 20150401; Y10T 428/249992
20150401; Y10T 428/249959 20150401; Y10T 428/249979 20150401; C08J
7/02 20130101; Y10S 530/814 20130101; Y10T 428/253 20150115; C08J
3/245 20130101; Y10T 428/254 20150115; Y10T 428/249981 20150401;
C08J 9/236 20130101; C08J 9/36 20130101; C08J 2207/12 20130101;
Y10T 428/25 20150115; Y10T 428/249982 20150401; C08J 2301/00
20130101; Y10T 428/249991 20150401; Y10T 428/249978 20150401; Y10T
428/249953 20150401 |
Class at
Publication: |
428/304.4 |
International
Class: |
B32B 003/26 |
Foreign Application Data
Date |
Code |
Application Number |
Jan 7, 1997 |
JP |
9-000600 |
Aug 7, 1997 |
JP |
9-227525 |
Aug 18, 1997 |
JP |
9-237761 |
Nov 25, 1997 |
JP |
9-340747 |
Dec 25, 1997 |
JP |
9-369666 |
Claims
1. A cellulosic particle body comprising cellulosic small particles
which are interconnected and having voids between the cellulosic
small particles.
2. The cellulosic particle body according to claim 1 wherein the
cellulosic small particles are interconnected in the presence of a
binder.
3. The cellulosic particle body according to claim 1 or 2 wherein
the cellulosic small particles have a mean particle diameter of
1.times.10.sup.-6 to 500.times.10.sup.-6 m.
4. The cellulosic particle body according to claim 1, 2 or 3
wherein the cellulosic small particles are porous particles.
5. The cellulosic particle body according to claim 1, 2, 3 or 4
wherein the particle body has a mean particle diameter of
10.times.10.sup.-6 to 5000.times.10.sup.-6 m.
6. A method of producing the cellulosic particle body according to
claim 1 which comprises dispersing cellulosic small particles in an
alkaline medium and contacting the resulting suspension with a
coagulating solution.
7. The method of producing a cellulosic particle body according to
claim 6 wherein the suspension is formed into droplets not
exceeding 5.times.10.sup.-3 m in diameter and then contacted with
the coagulating solution.
8. The method of producing a cellulosic particle body according to
claim 6 or 7 wherein a binder is coexistent with the
suspension.
9. The method of producing a cellulosic particle body according to
claim 8 wherein the suspension has a viscosity of 5.times.10.sup.-4
to 1.times.10.sup.4 Pa.s as measured at room temperature.
10. A perfusion type cellulosic particle body which comprises
porous cellulosic small particles interconnected to have void
between the cellulosic small particles as produced by dispersing
the porous cellulosic small particles in an alkaline medium to
prepare a suspension and contacting the resulting suspension with a
coagulating solution.
11. The perfusion type cellulosic particle body according to claim
10 wherein the coagulating solution is an acidic solution.
12. The perfusion type cellulosic particle body according to claim
11 wherein the alkaline medium has a pH value of not less than 13,
the concentration of cellulosic small particles in the suspension
is 50 to 75 volume %, and the acidic solution has a pH value of not
more than 1.
13. The perfusion type cellulosic particle body according to claim
10, 11 or 12 wherein the ratio of its mean particle diameter to the
mean diameter of the cellulosic small particles is less than
50.
14. The perfusion type cellulosic particle body according to claim
10, 11, 12 or 13 which has a mean particle diameter of not less
than 100.times.10.sup.-6 m and, when a housing packed with it is
irrigated at a linear velocity of not less than 3.times.10.sup.-4
m/s, produces a perfusion effect.
15. A method of producing a perfusion type cellulosic particle body
according to claim 10 wherein porous cellulose particles are
dispersed in an alkaline medium to prepare a suspension and the
resulting suspension is contacted with a coagulating solution.
16. The method of producing a perfusion type cellulosic particle
body according to claim 15 wherein the coagulating solution is an
acidic solution.
17. The method of producing a perfusion type cellulosic particle
body according to claim 16 wherein the alkaline medium has a pH
value of not less than 13, the concentration of cellulosic small
particles in the suspension is 50 to 75 volume % and the acidic
solution has a pH value of not more than 1.
18. A spherical type body which comprises crosslinked polymer
particles having diameters within a range of 0.1.times.10.sup.-6 m
to 10.times.10.sup.-3 m with a standard deviation of not greater
than 100% of their mean diameter and which has a diameter of
1.times.10.sup.-6 m to 100.times.10.sup.-3 m, and satisfies the
following conditions (A) to (C): (A) that said crosslinked polymer
particles are interconnected via an organic binder comprising a
non-crosslinked polymer; (B) that the surfaces of said crosslinked
polymer particles have area(s) not covered with said organic binder
but remaining exposed; (C) that voids exist between the
interconnected crosslinked polymer particles.
19. The spherical type body comprising the crosslinked polymer
particles according to claim 18 wherein the crosslinked polymer
particles are porous particles.
20. The spherical type body comprising crosslinked polymer
particles according to claim 18 or 19 wherein the crosslinked
polymer particles are composed of a crosslinked polymer containing
styrene as a monomer unit.
21. The spherical type body comprising the crosslinked polymer
particles according to claim 18, 19 or 20 wherein the crosslinked
polymer particles are composed of a crosslinked polymer containing
divinylbenzene as a component of crosslinking agent.
22. The spherical type body comprising crosslinked polymer
particles according to claim 18, 19, 20 or 21 wherein the organic
binder is a non-crosslinked polymer containing styrene as a monomer
unit.
23. A method of producing the spherical type body comprising
crosslinked polymer particles according to claim 18 which comprises
immersing crosslinked polymer particles having diameters within a
range of 0.1.times.10.sup.-6m to 10.times.10.sup.-3 m with a
standard deviation of not more than 100% of their mean diameter in
a solution containing an organic binder comprising a
non-crosslinked polymer in an organic solvent which does not
dissolve said crosslinked polymer particles but dissolves said
organic binder and then evaporating said organic solvent under
stirring to interconnect said crosslinked polymer particles via
said organic binder separating out on surfaces of said crosslinked
polymer particles.
24. An adsorbent for purification of a body fluid which comprises a
perfusion type carrier and, as immobilized thereon, a substance
having an affinity for a target substance in the body fluid.
25. The adsorbent for purification of a body fluid according to
claim 24 wherein the perfusion type carrier comprises the perfusion
type cellulosic particle body according to claim 10, 11, 12, 13 or
14.
26. The adsorbent for purification of a body fluid according to
claim 24 wherein the perfusion type carrier is the spherical type
body comprising the crosslinked polymer particles according to
claim 18, 19, 20, 21 or 22.
27. The adsorbent for purification of a body fluid according to
claim 24, 25 or 26 which has a mean particle diameter of not less
than 100.times.10.sup.-6 m and produces a perfusion effect when a
housing packed with it is irrigated at a linear velocity of not
less than 3.times.10.sup.-4 m/s.
28. The adsorbent for purification of a body fluid according to
claim 24, 25, 26 or 27 which comprises particles having diameters
within a range of 100.times.10.sup.-6m to 4000.times.10.sup.-6 m
and is intended for use in direct contact with whole blood.
29. The adsorbent for purification of a body fluid according to
claim 24, 25, 26, 27 or 28 wherein the ratio of the mean diameter
of said perfusion type particles to the mean diameter of
flow-through pores of the perfusion type carrier thereof is not
greater than 70.
30. The adsorbent for purification of a body fluid according to
claim 24, 25, 26, 27, 28 or 29 wherein the perfusion type carrier
has a height equivalent to a theoretical plate of not greater than
0.5 m as determined when it is irrigated with a solution containing
a target substance alone at a linear velocity of 1.times.10.sup.-4
m/s to 10.times.10.sup.-4 m/s.
31. An adsorption apparatus for purification of a body fluid
comprising the adsorbent according to claim 24, 25, 26, 27, 28, 29
or 30 as a packing.
32. A method of purifying a body fluid which comprises purifying
the body fluid by means of the adsorption apparatus for
purification of the body fluid according to claim 31.
Description
TECHNICAL FIELD
[0001] The present invention relates to a cellulosic particle body,
a method of producing said particle body, a spherical type body
which comprises crosslinked polymer particles interconnected with
the aid of an organic binder comprising a non-crosslinked polymer,
a method of producing said spherical type body, and an adsorbent
for purification of body fluids which is capable of removing a
target substance at a high speed in the therapy of hyperlipemia,
autoimmune diseases and immunity-mediated diseases and the
like.
BACKGROUND ART
[0002] A cellulosic particle body and a spherical type body
comprising a crosslinked polymer particle are in broad use in a
variety of fields, for example as a support for immobilization of
microbial cells or enzymes, an adsorbent matrix for perfumes and
pharmaceuticals, an adsorbent for purification of body fluids, a
cosmetic additive, a chromatographic stationary phase material,
etc. or, thorough introduction of a functional group, even as
various ion exchangers.
[0003] Much research has been undertaken into the cellulosic
particle body.
[0004] Japanese Kokai Publication Sho-63-90501 discloses a
technology which comprises blending an anionic water-soluble
compound with a mixture of viscose and a water-soluble
macromolecular compound to prepare a dispersion of microfine
particles, coagulating the dispersion under heating or with the aid
of a coagulant, regenerating it with an acid, and removing the
water-soluble macromolecular compound through a series of
coagulation, regeneration and aqueous washing to provide a porous
microfine cellulosic particle body with a mean particle diameter of
not greater than 3.times.10.sup.-4 m and a maximum pore volume
within a pore volume range of 2.times.10.sup.-8 to
8.times.10.sup.-7 m, with the total pore volume of all the pores
within said range being not less than 2.5.times.10.sup.-5
m.sup.3/kg. The particle body provided by the above technology is
such that the cellulosic particle body as such have fine pores.
[0005] Japanese Kokai Publication Sho-63-92602 discloses a
technology which comprises blending viscose, calcium carbonate and
a water-soluble anionic macromolecular compound to prepare a
dispersion of finely divided particles of calcium
carbonate-containing viscose, coagulating and neutralizing the
dispersion, and decomposing calcium carbonate with an acid to
provide a porous cellulosic particle body.
[0006] With those technologies, however, the cellulosic particle
body obtained are relatively small in diameter, so that in certain
applications such as a filler, an adsorbent, etc., it is difficult
to carry out a large-scale treatment at a high flow rate and if a
high-speed treatment is attempted, the cellulosic particle body
tend to be destroyed. Moreover, when such a cellulosic particle
body is used for the treatment of body fluids, plugging with blood
corpuscles tend to take place.
[0007] Accordingly there has been a demand for development of a
cellulosic particle body which would have sufficiently high
mechanical strength, be compatible with treatment at high flow
rates, exploit the pore structure of the cellulosic particle body
providing for a large surface area, and be free from the trouble of
plugging in the treatment of body fluids.
[0008] Meanwhile, in the field of body fluid treatment, a body
fluid purification method is being practiced as a therapeutic
technique comprising removal of a specific substance(s) from a body
fluid, which comprises passing the body fluid through an adsorption
device packed with an adsorbent immobilized a substance having an
affinity for a target substance on a carrier to thereby adsorb and
remove said substance. The method developed initially for this
purpose comprised passing whole blood over active charcoal,
particularly a coated charcoal particle to remove a target
substance. With advances in plasma perfusion membranes, various
adsorption devices for removing a target substance from separated
plasma have been developed.
[0009] Generally speaking, in body fluid purification therapy, the
treatment time is preferably as short as possible from the
standpoint of the patient's quality of life. For reducing the
treatment time, several approaches may be contemplated by using
ingenuity in the aspect of operating conditions with the adsorbent
material being held unchanged.
[0010] First, it may be contemplated to increase the flow rate of
the body fluid in the extracorporeal circuit so as to increase the
volume of the body fluid to be contacted with an adsorbent per unit
time. However, it will adversely affect the patient's quality of
life to excessively increase the flow rate of the body fluid
withdrawn from the patient's body and circulated extracorporeally.
The conventional flow rate of a body fluid for extracorporeal
circulation is 0.833.times.10.sup.-6 to 3.33.times.10.sup.-6
m.sup.3/s (50 to 200 ml/min.). Thus, there is a limit to the flow
rate of the body fluid which can be circulated
extracorporeally.
[0011] It may also be contemplated to increase the capacity of the
adsorption apparatus and thereby prolong the time of contact
between the body fluid and the adsorbent. However, as the device
capacity is increased, the volume of the body fluid existing
outside the body during treatment is increased to adversely affect
the patient's quality of life, with the result that the device
capacity cannot be increased beyond a certain limit. The capacity
of the conventional adsorption apparatus for purification of a body
fluid is 50.times.10.sup.-6 to 500.times.10.sup.-6 m.sup.3 (50 to
500 ml) at most.
[0012] Then it may also be contemplated to reduce the treatment
time by increasing the static adsorptivity of the adsorption
apparatus. The static adsorptivity means the saturated amount of
adsorption. As a means for enhancing the static adsorptivity, it
may be contemplated to enhance the static adsorptivity by
increasing the amount of adsorption per unit adsorbent. The factors
influencing the adsorption equilibrium relation are the substance
having an affinity for the target substance and the contact area
effective for adsorbing the target substance. However, said
substance having an affinity for the target substance is restricted
to a substance having a specific affinity for the particular target
substance. Furthermore, it is restricted to a substance
substantially not affecting the patient's physiology because the
objective is the treatment of a body fluid. It may also be
contemplated to increase the effective contact area but, as the
minimum requirement, this contact area must have pores receptive to
the target substance. Therefore, the maximum contact area of the
porous body having such pores is limited by the diameter and number
of pores. Thus, there is a limit to enhancing the static
adsorptivity by improving the above-mentioned adsorption
equilibrium relation.
[0013] As mentioned above, because of the restrictions associated
with the body fluid purification technology, it has been found
difficult to reduce the treatment time, with the amount of
adsorption maintained, by improving the device capacity, the flow
rate of a body fluid, and said static adsorptivity.
[0014] Lastly, it may be contemplated to reduce the treatment time
by improving the dynamic adsorptivity of the adsorption apparatus.
The dynamic adsorptivity means the magnitude of adsorption rate. As
a means for improving the dynamic adsorptivity, it may be
contemplated, for instance, to improve the dynamic adsorptivity by
optimizing the particle diameter of the adsorbent and the
intraparticle diffusion coefficient of the target substance.
[0015] Referring to the first approach, i.e. the method of reducing
the particle diameter of the adsorbent and, hence, said diffusion
distance to thereby improve the dynamic adsorptivity, reducing the
particle diameter of the adsorbent results in a reduced diameter of
the fluid flow passageway and an increased pressure loss so that
the risk for plugging is increased. Therefore, in consideration of
the safety of therapy, the particle diameter cannot be reduced too
much. Actually, the particle diameter of the conventional adsorbent
for plasma perfusion is 50.times.10.sup.-6m to less than
1000.times.10.sup.-6 m and that for direct blood perfusion is
100.times.10.sup.-6 m to less than 4000.times.10.sup.-6 m.
[0016] Referring to the second approach, that is the method which
comprises increasing the diffusion coefficient of the target
substance within the adsorbent for insuring a fast transfer of the
target substance within the adsorbent to hereby improve the dynamic
adsorptivity, this method is also subject to the following
restrictions. In the case of the conventional adsorbent for
purification of a body fluid which depends on rate-determining
diffusion, once the target substance is established, its diffusion
coefficient has a constant value according to the structure of the
adsorbent so that it becomes necessary to add ingenuity to the
adsorbent structure. However, even if the structure is optimized,
the diffusion coefficient of the target substance within the
adsorbent does not increase beyond the diffusion coefficient in the
body fluid where no steric hindrance exists and, therefore, this
method is also limited.
[0017] Thus, as far as the conventional adsorbent for purification
of a body fluid is concerned, there is a limit to improving the
dynamic adsorptivity by increasing the particle diameter of the
adsorbent and the intraparticle diffusion coefficient of the target
substance, with the result that the treatment time can hardly be
reduced.
[0018] On the other hand, while it is difficult to apply them to
the purification of a body fluid, there exists some adsorbent
materials which, when used as chromatographic carriers for
immobilization of a substance having an affinity for the target
substance, can be expected to achieve an improved dynamic
adsorptivity.
[0019] The principles relating to dynamic adsorptivity are now
explained in the first place. As an indicator of dynamic
adsorptivity, it is common practice to use a breakthrough curve
which represents the time course of change in the concentration of
the target substance at the exit of an adsorption apparatus when a
solution containing said target substance in a given concentration
is passed at a constant flow rate. In estimating the dynamic
adsorptivity of an adsorption apparatus under operating conditions,
it is preferable to keep the linear velocity of flow within the
adsorption apparatus constant, that is to say a constant state of
flow around the adsorbent. It should be noted that the term "linear
velocity within the adsorption apparatus" is used in this
specification to mean the rate of transfer (m/s) of the mobile
phase in the adsorption apparatus.
[0020] On the other hand, the theoretical plate number is generally
used as an indicator of the performance of a column packed with an
adsorbent not carrying an adsorbate thereon (a packed column). The
theoretical plate number means the minimum multiples of column
height which would be required for a target substance to attain an
adsorption-desorption equilibrium when a solution containing it is
passed through the packed column.
[0021] According to Kato et al. [Shigeo Kato, et el., Journal of
Fermentation and Bioengineering, 78, 246 (1994)], the
above-mentioned breakthrough curve representing the dynamic
adsorptivity of an adsorption apparatus can be correlated with the
above-mentioned theoretical plate number as an indicator of the
performance of a packed column by the following three expressions.
1 C C 0 = 1 - - N { 1 + N + ( N ) 2 2 ! + + ( N ) N - 1 ( N - 1 ) !
} t - = V F = q 0 C 0
[0022] wherein t represents time (in seconds); C represents the 3
concentration [kg/m.sup.3] of a target substance at the exit of an
adsorption apparatus, which is a time-dependent variable; Co
represents the concentration [kg/m.sup.3] of the target substance
entering the adsorption apparatus, which is a constant; V
represents the volume of the adsorption apparatus or the volume of
a packed column [m.sup.3], which is a constant; q.sub.0 represents
the amount of adsorption at equilibrium [kg/m.sup.3] at Co, i.e.
the amount of adsorption which does not increase any further when a
solution of the concentration C.sub.0 is passed through the
adsorption apparatus, which is a constant; F represents the flow
rate [m.sup.3/sec.] of solution selected so as to be equal to the
linear velocity within the adsorption apparatus under operating
conditions, which is a constant; N represents the theoretical plate
number as found for the target substance when a solution containing
it is passed through the packed column at the same flow rate F as
that found for the same target substance when the same solution is
passed through the adsorption apparatus, which is a constant;
t.sup.- represents the average residence time [seconds] of the
target substance in the column; .theta. represents the percentage
of t relative to t.sup.-; and .alpha. is a parameter representing
the adsorption efficiency of an adsorbent.
[0023] To demonstrate the influence of the theoretical plate number
on the breakthrough curve, suitable values were substituted into
the above expressions for calculation. The result is shown in FIG.
1. Referring to FIG. 1, the amount of adsorption per unit volume q
[kg/m.sup.3]of the absorption apparatus up to each point of time
t/t.sup.- represents the area above the breakthrough curve, that is
the value which can be found by integrating {1-(C/C.sub.0)} up to
that point of time and dividing the result by the volume of the
adsorption apparatus. FIG. 2 shows the time course of the
absorption amount q with respect to q.sub.0 as calculated by said
integration. It can be understood from FIG. 2 that the larger the
theoretical plate number of the packed column is, the larger is the
adsorption amount which can be adsorbed in a given time and the
shorter is the time required for adsorbing a given amount of the
substance, indicating that the dynamic adsorptivity of the
adsorption apparatus is improved. It is, therefore, clear that the
dynamic adsorptivity of an adsorption apparatus can be improved by
increasing the theoretical plate number of the packed column.
[0024] Furthermore, the theoretical plate number of a packed column
is dependent on the minimum column height which is necessary for
attaining an adsorption-desorption equilibrium (the height
equivalent to a theoretical plate) and the height of the packed
column and can be expressed by the following equation. 2 N = L
HETP
[0025] wherein L [m] represents the height of a packed column and
HETP [m] represents the height equivalent to a theoretical plate.
Since the column height is fixed, increasing the theoretical plate
number of the packed column can be attained by reducing the height
equivalent to a theoretical plate which is characteristic of the
carrier packed, and the dynamic adsorptivity of an adsorption
apparatus can be improved by this method. Whereas the theoretical
plate number is dependent on the housing geometry and other
factors, the height equivalent to a theoretical plate is a
characteristic which is solely dependent upon the properties of the
adsorbent or solid phase. Stated differently, in discussing the
height equivalent to a theoretical plate, it is permissible to use
a packed column geometrically different from the adsorption
apparatus used for construction of the breakthrough curve, although
the linear velocity of flow in the packed column should be equal to
that in the adsorption apparatus.
[0026] Meanwhile, it is known that when a housing is packed with a
particle having flow-through pores extending through each particle
and sub-pores communicating with said flow-through pores and
smaller in diameter than the flow-through pores as a stationary
phase material for chromatography, a stationary phase material for
affinity chromatography or a support for immobilization of an
enzyme and a solution is passed through the packing at a suitable
flow rate, the migration of a solute within the packing is rapid
(perfusion effect) compared with the usual particulate adsorbent
not having flow-through pores so that the objective operation can
be accomplished at a high speed [Japanese Kohyo Publication
Hei-4-500726, Japanese Kohyo Publication Hei-6-507313, N. B. Affean
et al.: Journal of Chromatography, 519, 1 (1990), Shigeo Kato et
al.: Journal of Fermentation and Bioengineering, 78, 246 (1994)].
In this specification, a carrier having a structure such that a
flow passing through its particles occurs when there is a flow
around said carrier particles and that, when there is a flow of a
liquid such as a body fluid around the carrier particles, a portion
of the flow passes through the carrier particles owing to the
resultant pressure gradient is referred to as a perfusion type
carrier. The above-mentioned carrier having flow-through pores and
sub-pores is a perfusion type carrier.
[0027] The perfusion type carrier is known to be a stationary phase
with a smaller height equivalent to a theoretical plate. In other
words, because of occurrence of flows passing through the carrier
particles, the measured height equivalent to a theoretical plate of
such a perfusion type carrier is smaller than that of the
conventional carrier in which the mass transfer of the target
substance depends solely on diffusion. Therefore, an adsorption
apparatus packed with an adsorbent comprising a substance having an
affinity for the target substance as immobilized on a perfusion
type carrier shows an improved dynamic adsorptivity.
[0028] As a typical perfusion type carrier, there is known POROS
(trade name), chromatographic carriers available from Perceptive
Biosystems (particle diameters 10.times.10.sup.-6 m,
20.times.10.sup.-6 m, 5.times.10.sup.-6m) (Japanese Kohyo
Publication Hei-4-500726). However, since those carriers are
intended to be used for chromatography, they are available only in
small particle diameter ranges in consideration of the ease of
packing and flow. Therefore, when a container is packed with this
kind of carrier and a fluid from a fermentation tank, a slurry,
blood or the like is passed through it, plugging tends to take
place owing to the small particle diameter. Moreover, in order to
attain a perfusion effect, a solution must be passed at a high
linear velocity of not less than 2.8.times.10.sup.-3 m/s.
[0029] Heretofore unknown is a perfusion type carrier which is
large in particle diameter and provides a perfusion effect even
when a solution is passed at a low speed. Neither known to this day
is a cellulosic perfusion type carrier. For example, POROS (trade
name) mentioned above is a carrier comprising conglomerates of fine
particles of a styrene-divinylbenzene copolymer.
[0030] On the other hand, porous particles of crosslinked polymers
have large specific surface areas and have been used broadly as
chromatographic column packings or adsorbents and, furthermore,
such particles have been actively developed. Such conglomerates of
crosslinked polymer particles may have minute voids between the
constituent crosslinked polymer particles of the conglomerate and,
therefore, express a variety of functions not obtainable with
discrete crosslinked polymer particles. The following technology is
available for the construction of spherical type bodies or
conglomerates having pores between the adjacent constituent
crosslinked polymer particles.
[0031] Japanese Kokai Publication Hei-9-25303, for instance,
discloses a method for interconnecting particles by way of
polymerization which comprises polymerizing a monomer on the
surface of crosslinked polymer particles. More particularly, this
method comprises dispersing crosslinked polymer particles in a
dispersion medium containing a monomer, polyvinyl alcohol, etc. to
let the monomer penetrate into the crosslinked polymer particles
and then polymerizing the monomer to thereby interconnect the
crosslinked polymer particles.
[0032] However, because the crosslinked polymer particles are
bonded to one another by polymerization, this method requires a
complicated polymerization procedure and, moreover, is restricted
in the diameter of crosslinked polymer particles which can be
bonded together (100.times.10.sup.-6 m at most). In addition, since
the monomer so polymerized covers up the entire surface of the
crosslinked polymer particles, the inherent functions of the
particles are impaired. Another disadvantage is that, after use,
the crosslinked polymer particles cannot be reused.
[0033] The present invention has for its object to provide a
carrier or adsorbent which overcomes the above-mentioned
disadvantages.
[0034] More particularly, in the light of the above-mentioned arts,
it is an object of the present invention to provide a cellulosic
particle body which is suited for use in treatments at high flow
rates and has excellent mechanical strength and a large surface
area and a method of producing said particle body.
[0035] In the light of the above-mentioned arts, it is a further
object of the invention to provide a cellulosic particle body which
can be provided in a relatively large particle diameter range and
produces a perfusion effect even when a solution is passed at a
comparatively low linear velocity and a method of producing said
particle body.
[0036] In the light of the above-mentioned arts, it is a still
another object of the invention to provide a connected particle
body comprising assemblages of crosslinked polymer particles with
minute interparticle spaces which (1) can be manufactured by a
simpler procedure as compared with the prior art, (2) is less
restricted in the available particle diameter of assemblages of
crosslinked polymer particles as compared with the prior art, (3)
has an exposed area uncovered by a monomer polymerized on the
surface of crosslinked polymer particles and consequently allowing
expression of the inherent functions of said particles, and (4)
permits reusing of the crosslinked polymer particles from the
assemblages after use.
[0037] It is a still further object of the invention to provide an
adsorbent for purification of body fluids which is capable of
removing a target substance at a high speed so as to reduce the
treatment time with the amount of adsorption maintained at a high
level.
SUMMARY OF THE INVENTION
[0038] The present invention relates to a cellulosic particle body
comprising interconnected cellulosic small particles and having
voids between particles and to a method of producing said
cellulosic particle body which comprises dispersing cellulosic
small particles in an alkaline medium and contacting the resulting
suspension with a coagulating solution. In this specification, the
above technology will be referred to as the first invention.
[0039] In another aspect, the present invention relates to a
perfusion type cellulosic particle body which comprises porous
cellulosic small particles interconnected to have void between the
cellulosic small particles as produced by dispersing the porous
cellulosic small particles in an alkaline medium to prepare a
suspension and contacting the resulting suspension with a
coagulating solution and to a method of producing said perfusion
type cellulosic particle body which comprises dispersing porous
cellulosic small particles in an alkaline medium and contacting the
resulting suspension with a coagulating solution. In this
specification, this technology will be referred to as the second
invention.
[0040] The present invention further relates to a spherical type
body which comprises crosslinked polymer particles having diameters
within a range of 0.1.times.10.sup.-6 to 100.times.10.sup.-3m with
a standard deviation of not greater than 100% of their mean
diameter and which has a diameter of 1.times.10.sup.-6 m to
100.times.10.sup.-3 m, and satisfies the following conditions (A)
to (C):
[0041] (A) that said crosslinked polymer particles are
interconnected via an organic binder comprising a non-crosslinked
polymer;
[0042] (B) that the surfaces of said crosslinked polymer particles
have area(s) not covered with said organic binder but remaining
exposed;
[0043] (C) that voids exist between the interconnected crosslinked
polymer particles.
[0044] The present invention further relates to a method of
producing the spherical type body comprising crosslinked polymer
particles which comprises immersing crosslinked polymer particles
having diameters within a range of 0.1.times.10.sup.-6 m to
10.times.10.sup.-3 m with a standard deviation of not more than
100% of their mean diameter in a solution containing an organic
binder comprising a non-crosslinked polymer in an organic solvent
which does not dissolve said crosslinked polymer particles but
dissolves said organic binder and then evaporating said organic
solvent under stirring to interconnect said crosslinked polymer
particles via said organic binder separating out on surfaces of
said crosslinked polymer particles.
[0045] The spherical type body mentioned above need only be
substantially spherical and includes a spheroidal body with a ratio
of minor axis/major axis up to about 0.7. In this specification,
this technology will be referred to as the third invention.
[0046] The present invention relates, in a further aspect, to an
adsorbent for purification of body fluids which comprises a
perfusion type carrier and, as immobilized thereon, a substance
having an affinity for a target substance, to an adsorption
apparatus for purification of body fluids which comprises a housing
packed with said adsorbent and to a method of purifying a body
fluid using said adsorption apparatus for purification of body
fluids. In this specification, the above technology will be
referred to the fourth invention.
BRIEF DESCRIPTION OF THE DRAWINGS
[0047] FIG. 1 is a diagram showing the effect of the theoretical
plate number on the breakthrough curve.
[0048] FIG. 2 is a diagram showing the time course of change in the
amount of adsorption relative to q.sub.0.
[0049] FIG. 3 is a photograph (.times.100) showing the surface of
the cellulosic particle body according to Example 1.
[0050] FIG. 4 is a photograph (.times.100) showing the
cross-section of the cellulosic particle body according to Example
1.
[0051] FIG. 5 is a photograph (.times.100) showing the
cross-section of the cellulosic particle body according to Example
1.
[0052] FIG. 6 is a photograph (.times.5000) showing the
cross-section of the cellulosic particle body according to Example
1.
[0053] FIG. 7 is a photograph (.times.100) showing the surface and
cross-section of the cellulosic particle body according to Example
3.
[0054] FIG. 8 is a photograph (.times.200) showing the surface and
cross-section of the cellulosic particle body according to Example
3.
[0055] FIG. 9 is a photograph (.times.1000) showing the surface of
the cellulosic particle body according to Example 3.
[0056] FIG. 10 is a photograph (.times.5000) showing the
cross-section of the cellulosic particle body according to Example
3.
[0057] FIG. 11 is a photograph (.times.40) showing the surface of
the cellulosic particle body according to Example 6.
[0058] FIG. 12 is a photograph (.times.40) showing the
cross-section of the cellulosic particle body according to Example
6.
[0059] FIG. 13 is a photograph (.times.500) showing the
cross-section of the cellulosic particle body according to Example
6.
[0060] FIG. 14 is a photograph (.times.5000) showing the
cross-section of the cellulosic particle body according to Example
6.
[0061] FIG. 15 is a photograph (.times.200) showing the surface of
the cellulosic particle body according to Example 7.
[0062] FIG. 16 is a photograph (.times.1000) showing the surface of
the cellulosic particle body according to Example 7.
[0063] FIG. 17 is a photograph (.times.5000) showing the surface of
the cellulosic particle body according to Example 7.
[0064] FIG. 18 is an elution curve of low-density lipoprotein in
Comparative Example 5.
[0065] FIG. 19 is an elution curve of low-density lipoprotein in
Example 8.
[0066] FIG. 20 is a photograph (.times.12) showing the surface of
the spherical type body according to Example 9.
[0067] FIG. 21 is a photograph (.times.200) showing the surface of
the spherical type body according to Example 9.
[0068] FIG. 22 is a photograph (.times.200) showing the surface of
the carrier according to Example 10.
[0069] FIG. 23 is a photograph (.times.5000) showing the surface of
the carrier according to Example 10.
[0070] FIG. 24 is a photograph (.times.200) showing the
cross-section of the carrier according to Example 10.
[0071] FIG. 25 is a photograph (.times.5000) showing the
cross-section of the carrier according to Example 10.
[0072] FIG. 26 is an elution curve of low-density lipoprotein in
Reference Example 2.
[0073] FIG. 27 is an elution curve of low-density lipoprotein in
Comparative Reference Example 3.
DETAILED DESCRIPTION OF THE INVENTION
[0074] The first invention is now described in detail.
[0075] The cellulosic small particles mentioned above are particles
of a cellulosic substance selected from among, for example,
cellulose, cellulose derivative and regenerated cellulose.
[0076] The cellulose mentioned above is not particularly restricted
but includes degreased cotton fiber, hemp pulp, wood pulp, and
purified celluloses available from said pulps, among others.
[0077] The cellulose derivative mentioned above is not particularly
restricted but includes a compound containing partially esterified
hydroxyl groups (ester derivative); a compound containing
etherified hydroxyl groups (ether derivative), among others.
[0078] The ester derivative of cellulose is not particularly
restricted but includes cellulose acetate, cellulose propionate,
nitrocellulose, cellulose phosphate, cellulose acetate butyrate,
cellulose nitrate, dithiocarboxylic esters of cellulose (e.g.
viscose rayon), among others.
[0079] The above-mentioned ether derivative of cellulose is not
particularly restricted but includes methylcellulose,
ethylcellulose, benzylcellulose, tritylcellulose,
cyanoethylcellulose, carboxymethylcellulose, carboxyethylcellulose,
aminoethylcellulose and oxyethylcellulose, among others.
[0080] The regenerated cellulose mentioned above is a cellulosic
material obtainable by converting cellulose to an easily moldable
derivative and reconverting it to cellulose after molding and
specifically includes but is not limited to the various cellulosic
materials available upon hydrolysis of ester derivatives of
cellulose such as cellulose acetate and cellulose propionate.
[0081] The cellulosic small particles mentioned above may be porous
or non-porous but is preferably porous. When the cellulosic small
particles are porous, the particles will present with a relatively
greater surface area per unit volume.
[0082] As the above-mentioned cellulosic small particles, there can
be utilized those particles which are conventionally used in
applications such as gel filtration stationary phases, cellulosic
ion exchanger materials, stationary phase materials for affinity
chromatography, polymer flocculants, adsorbents for purification of
body fluids, cosmetic additives, and so on.
[0083] The cellulosic small particles can be produced by the
conventional technology. For example, said porous cellulosic small
particles can be produced by the methods described in Japanese
Kokai Publications Sho-63-90501, Sho-63-92602 and so on. More
particularly, the following procedures, for instance, can be
utilized.
[0084] (1) A basic aqueous polymer solution containing cellulose
xanthate and a water-soluble polymer is mixed with a water-soluble
anionic polymer to prepare a particle dispersion of basic aqueous
polymer solution, which is then heated or treated with a cellulose
xanthate coagulant so as to cause the cellulose xanthate contained
in the dispersion to be coagulated as fine particles. Since those
cellulose xanthate particles contain said water-soluble polymer,
the polymer is then removed. Then, the cellulose xanthate particles
are neutralized with an acid for regeneration of cellulose to
provide the objective cellulosic small particles.
[0085] As an alternative, the coagulation of cellulose xanthate can
be effected by adding an acid to said dispersion. In this case,
after removal of said water-soluble polymer, the acid added is
neutralized for regenerating cellulose to provide the objective
cellulosic small particles.
[0086] (2) A viscose, calcium carbonate and a water-soluble anionic
polymer are blended to prepare a dispersion of viscose fine
particles containing calcium carbonate, which is then heated or
treated with a coagulant to cause the viscose in said dispersion to
be coagulated. The dispersion is then neutralized with an acid to
give fine particles of cellulose. The cellulose particles are
separated from the dispersion and, after removal of the calcium
carbonate by acidolysis, dried to provide the objective cellulosic
small particles.
[0087] The mean diameter of said cellulosic small particles is
preferably in the range of 1.times.10.sup.-6 to 500.times.10.sup.-6
m. If it is less than 1.times.10.sup.-6 m, it will be difficult to
provide sufficient voids among the cellulosic small particles
constituting the cellulosic particle body. On the other hand, if
the upper limit of 500.times.10.sup.-6 m is exceeded, the great
load of each the cellulosic small particles may not allow the
product particle body to maintain its constituent cellulosic small
particles in the intact agglomerated condition. The more preferred
range is 5.times.10.sup.-6 to 100.times.10.sup.-6 m.
[0088] The cellulosic particle body of the first invention
comprises a conglomerate of said cellulosic small particles
interconnected so as to have voids between the cellulosic small
particles.
[0089] The voids mentioned above are formed internally of the
cellulosic particle body and, therefore, the cellulosic particle
body of the first invention is provided with a multiplicity of
minute pores, some of which are exposed on the surface while the
others distributed within the particle body.
[0090] Preferably the cellulosic particle body of the first
invention is a conglomerate of cellulosic small particles
interconnected in the presence of a binder. The inventors of the
present invention found that the interposition of a binder between
individual cellulosic small particles leads to a marked increase in
the strength of the cellulosic particle body as compared with the
corresponding particle body assembled without a binder. The use of
a binder provides for the additional advantage that the strength of
the particle body can be controlled by adjusting the amount of the
binder.
[0091] The binder mentioned above is not particularly restricted
but may for example be an organic compound, an inorganic compound,
a synthetic organic low molecular compound, a synthetic inorganic
low molecular compound, a naturally-occurring organic low molecular
compound, a naturally-occurring inorganic low molecular compound, a
synthetic organic high molecular compound, a synthetic inorganic
high molecular compound, a naturally-occurring organic high
molecular compound or a naturally-occurring inorganic high
molecular compound.
[0092] The inorganic compound mentioned above is not particularly
restricted but may for example be a compound which, upon contact
with a coagulating solution, forms a three-dimensional network
structure. As an example of such inorganic compound there can be
mentioned water glass. Water glass generally means a concentrated
aqueous solution of either sodium oxide or potassium oxide and
silicon dioxide. This solution reacts with various metal salts to
allow growth of a precipitate in the solution. When cellulosic
small particles and water glass (intended to function as a binder)
are dispersed in an alkaline medium and the resulting suspension is
brought into contact with an aqueous solution of a metal salt
(intended to function as a coagulating solution), a precipitate is
formed to give rise to a cellulosic particle body comprising
interconnected cellulosic small particles.
[0093] The synthetic inorganic high molecular compound is not
particularly restricted but includes inorganic polymer flocculants
such as poly(aluminum chloride), poly(aluminum sulfate),
poly(ferric chloride), poly(ferric sulfate) and so on.
[0094] The synthetic organic high molecular compound mentioned
above is not particularly restricted but includes various organic
polymer flocculants such as polyacrylonitrile, polyacrylamide,
poly(sodium acrylate) and acrylic acid-acrylamide copolymer, among
others.
[0095] The naturally-occurring organic high molecular compound
mentioned above is not particularly restricted but includes, for
example, cellulosic substances, starch and starch derivatives, and
soluble salts of alginic acid.
[0096] As the binders mentioned above, among these, substances
having functional groups capable of undergoing hydrogen bonding
with the hydroxyl groups of the cellulose molecule or cellulose
derivative molecule are preferred. Still more preferred are
substances structurally resembling cellulose. More particularly,
cellulosic substances, starch and starch derivatives and soluble
salts of alginic acid can be mentioned, among others. Those
substances have structure similar to cellulose, having glucose
structures with attendant hydroxyl groups, so that they may undergo
hydrogen bonding with the hydroxyl groups of the cellulose molecule
or cellulose derivative molecule. Those binders are now described
in detail.
[0097] The cellulosic substance mentioned above may be either the
same substance as or different from said cellulose molecule
constituting said cellulosic small particles, such as cellulose,
cellulose derivative, regenerated cellulose molecule and the
like.
[0098] The cellulose mentioned just above is not particularly
restricted but includes the species mentioned hereinbefore.
[0099] The cellulosic derivative mentioned above is not
particularly restricted but includes the species mentioned
hereinbefore.
[0100] The regenerated cellulose mentioned above is not
particularly restricted but includes the species mentioned
hereinbefore.
[0101] The starch and starch derivative mentioned above are not
particularly restricted but include various esters of starch, e.g.
acetate ester, succinate ester, nitrate ester, phosphate ester,
xanthate ester, etc.; various ethers of starch, e.g. allyl ether,
methyl ether, carboxymethyl ether, carboxyethyl ether, hydroxyethyl
ether, hydroxypropyl ether, etc.; and degradation products of
native starch, such as pyrodextrin, starch oxide, etc.
[0102] The pyrodextrin mentioned above is not particularly
restricted but includes white dextrin, yellow dextrin, and British
gum.
[0103] The starch oxide mentioned above is not particularly
restricted but includes hypochlorous acid-oxidized starch and
dialdehyde-starch, among others.
[0104] The soluble salt of alginic acid mentioned above is not
particularly restricted but includes sodium alginate, for
instance.
[0105] It is known that an aqueous solution of said soluble salt of
alginic acid forms an insoluble salt when brought into contact with
an aqueous solution of a divalent or higher valence metal salt
except for magnesium and mercury ions. Since this insolubilization
occurs instantaneously, dripping an aqueous solution of a soluble
salt of alginic acid into an aqueous solution of a divalent metal
salt such as calcium chloride results in the easy formation of an
insoluble salt. For example, when cellulosic small particles and
said soluble salt of alginic acid (intended to function as a
binder) are dispersed in an alkaline medium and the resulting
suspension is contacted with an aqueous solution of a divalent or
higher valence metal salt excepting magnesium and mercury ions
(intended to function as said coagulating solution), the insoluble
salt is formed to provide said cellulosic particle body comprising
interconnected cellulosic small particles.
[0106] The binders mentioned above, inclusive of said cellulosic
substances, starch and starch derivatives, can be used each
independently or in a combination of two or more species.
[0107] It is also possible to use a binder which is a conjugate of
two or more molecules constituting a binder. More particularly, the
copolymer of said synthetic organic high molecular compound with
said naturally-occurring organic high molecular compound, for
example an acrylamide-carboxymethylcellulose graft polymer, can be
mentioned by way of example.
[0108] Referring to said cellulosic particle body, the mode of
interconnection of individual cellulosic small particles need not
necessarily be covalent bonding but may be any binding mode by
which the resulting conglomerate of cellulosic small particles may
substantially retain its integral form. Thus, in addition to said
covalent bonding, the mode of interconnection of cellulosic small
particles includes an intertwining of cellulose or cellulose
derivative molecules, hydrogen bonding and other modes of chemical
bonding.
[0109] For example, cellulose consists of D-glucopyranose units
connected by .beta.1.fwdarw.4 glycosidic bonds and has three
hydroxyl groups per glucose unit of the backbone chain. Those
hydroxyl groups are considered to be forming hydrogen bonds between
molecular chains or intramolecularly and hydrogen bonds between
acetal oxygen atoms. In said cellulose derivatives, too,
unsubstituted hydroxyl groups appear to be playing the same
roles.
[0110] When the cellulosic particle body comprises a conglomerate
of cellulosic small particles interconnected in the presence of a
binder, the connection by molecular intertwining between the
cellulosic small particle and the binder, the connection by
chemical bonding such as hydrogen bonding between the cellulose
small particle, the binder and so on are also included.
[0111] Observation of the mutually connected state of particles in
the cellulosic particle body reveals the following three possible
cases.
[0112] (1) The adjacent particles are interconnected by point
contact of their surfaces.
[0113] (2) The adjacent particles adhere each other and are
interconnected by planar contact of their surfaces.
[0114] (3) In appearance, the surfaces of adjacent particles are
apart from each other but bridged by filamentous or other
structures.
[0115] When the cellulosic particle body comprises a conglomerate
of cellulosic small particles interconnected in the presence of a
binder, the above state (3) may be included and, in this case, the
binder is used as said filamentous or other structures.
[0116] The spaces formed between particles in any of the above
three cases are the voids among cellulosic small particles in the
cellulosic particle body according to this invention.
[0117] The preferred mean particle diameter of the cellulosic
particle body of the invention is 10.times.10.sup.-6to
5000.times.10.sup.-6 m and can be judiciously selected according to
the intended application.
[0118] When the mean diameter of said cellulosic small particles is
not less than 1.times.10.sup.-6 m, the cellulosic particle body
comprising such interconnectd cellulosic small particles can be a
stable particle body in the case of a diameter thereof of not less
than 10.times.10.sup.-6 m. When the mean particle diameter of the
cellulosic particle body is less than 10.times.10.sup.-6 m, the
resulting cellulosic particle body may not be stable enough because
it has few interconnecting points and is prone to destruction.
[0119] The specific surface area of said cellulosic particle body
in dry condition is preferably not less than 2.times.10.sup.4 m
2/kg. If it is less than 2.times.10.sup.4 m2/kg, the effective area
available for the intended application will be too small. The still
more preferred range is not less than 5.times.10.sup.4
m.sup.2/kg.
[0120] The geometry of said cellulosic particle body is not
particularly restricted provided that it comprises a conglomerate
of individual cellulosic small particles interconnected to have
voids between particles, thus may for example be spheroidal or
substantially spherical.
[0121] The cellulosic particle body according to the first
invention can be produced by dispersing said cellulosic small
particles in an alkaline medium and contacting the resulting
suspension with a coagulating solution.
[0122] The alkaline medium mentioned above is not particularly
restricted but includes, among others, an aqueous solution of
sodium hydroxide, an aqueous solution of lithium hydroxide, an
aqueous solution of potassium hydroxide, an aqueous solution of
cesium hydroxide and an aqueous solution of rubidium hydroxide.
[0123] For adjusting its viscosity, said alkaline medium may be
supplemented with a thickener such as glycerin.
[0124] The hydrogen ion concentration of said alkaline medium is
not particularly restricted provided that it is within the alkaline
range but is preferably not below pH 9. The more preferred pH range
is not less than 10 and the still more preferred range is not less
than 12. When the pH of the medium is less than 10, contacting said
suspension of cellulosic small particles with the coagulating
solution may result in a failure to interconnect the particles with
the individual particles remaining dispersed.
[0125] The pH values mentioned in this specification are values
given by pH=-log.sub.10 [H.sup.+] assuming that the degree of
dissociation of an acid or an alkali in aqueous solution=1 and
[H.sup.+]x[OH.sup.-]=10.sup.-- 14.
[0126] The preferred concentration of said suspension of cellulosic
small particles is 50 to 75 volume %.
[0127] The above-mentioned concentration of said suspension means
the percentage of the total volume of cellulosic small particles
occurring in a suspension based on the volume of the suspension.
Here, the concentration of the residue available upon filtration of
the above suspension is assumed to be 100 volume %. When the
cellulosic small particles are porous particles and have a large
water content, their apparent specific gravity is not much
different from the specific gravity of the solution so that volume
% is substantially equivalent to weight %.
[0128] When the suspension concentration of cellulosic small
particles is less than 50 volume %, contacting droplets of the
suspension with a coagulating solution yields a fragment-like
cellulosic particle body with weak strength. When the concentration
exceeds 75 volume %, no smooth-surfaced liquid droplets are
obtained so that the cellulosic particle body will be a coarse
block. The more preferred concentration is 60 to 70 volume %.
[0129] The suspension mentioned above may be a dispersion of
cellulosic small particles and a binder in an alkaline medium.
[0130] The method of suspending said binder is not particularly
restricted but may for example be the method which comprises
dissolving said binder in said alkaline medium and blending the
resulting solution or suspension with said cellulosic small
particles.
[0131] The proper amount of addition of said binder cannot be
stated in general terms because it depends on the molecular weight
of the binder, among other factors. Usually, however, the preferred
concentration of the binder in the suspension of prepared by
dispersing cellulosic small particles and binder in said alkaline
medium is 0.01 to 50 weight %. When the concentration of the binder
is less than 0.01 weight %, the binder does not sufficiently
discharge the function of a binder so that, compared with the
cellulosic particle body prepared without the aid of a binder, the
binder does not contribute in any significant measure to the
mechanical strength of the cellulosic particle body. When the
concentration exceeds 50 weight %, the excess of the binder may
eliminate the spaces among the constituent cellulosic small
particles. The more preferred concentration range is 0.1 to 30
weight % and the still more preferred range is 0.2 to 20 weight
%.
[0132] As mentioned above, the preferred mean diameter of
cellulosic small particles is 1.times.10.sup.-6 to
500.times.10.sup.-6 m. Within this range, the trouble of the binder
added filling up the interparticle spaces, which is encountered
when the mean particle diameter is smaller than 1.times.10.sup.-6
m, can be avoided.
[0133] The preferred viscosity of the suspension dispersing said
cellulosic small particles and binder in said alkaline medium at
room temperature is 5.times.10.sup.-4 to 1.times.10.sup.4 Pa.s.
When the viscosity is below 5.times.10.sup.-4 Pa.s, droplets of the
suspension contacting the coagulating solution tend to be deformed
so that no spherical type body can be obtained. When the viscosity
exceeds 1.times.10.sup.4 Pa.s, droplets of the suspension may be
hard to be deformed so that a spherical conformation cannot be
given.
[0134] The method and apparatus for viscosity measurement are not
particularly restricted provided that any of the conventional
techniques and instruments by the viscosity over the range of
5.times.10.sup.-4 to 1.times.10.sup.4 Pa.s can be determined. The
term "viscosity" as used herein means the viscosity defined in JIS
Z 8802-1959. Thus, it is the internal resistance of a liquid which
is expressed by the magnitude of the strain generated in the
direction of shear rate per unit area in a plane perpendicular to
the direction of the shear which exists in the liquid and its
dimension is (mass)/(length.times.time). All viscosities within the
above viscosity range need not be measured with one and the same
apparatus. Moreover, the method and apparatus for viscosity
measurement may be expedient ones, the accuracy of which may for
example be about 10%.
[0135] The apparatus for viscosity measurement is not particularly
restricted but includes a capillary viscometer, a short-tube
viscometer, a falling-ball viscometer, a tumbling-ball viscometer,
a falling-cylinder viscometer, a coaxial-cylinder rotating
viscometer, and an air-cell viscometer. When the viscosity of the
solution is within the range of 5.times.10.sup.-4 to
1.times.10.sup.2 Pa.s, the air-cell viscometer is preferably used.
The coaxial-cylinder rotating viscometer is preferred for
determination within the range of 1 to 1.times.10.sup.4 Pa.s.
[0136] As said cellulosic small particles are suspended in said
alkaline medium, the cellulose or cellulose derivative becomes
alkali cellulose and swells in the surface layer of said cellulosic
small particles and, at the same time, the hydrogen bonds are
cleaved so that the mobility of the cellulose or cellulose
derivative molecules is remarkably increased. In case a binder is
concomitantly present, the suspension becomes more ready to take up
the binder.
[0137] The duration of suspending cellulosic small particles in
said alkaline medium is preferably not less than 1 minute. When it
is less than 1 minute, it is difficult to insure swelling of the
cellulose or cellulose derivative as alkali cellulose on the
surface of particles so that the cellulosic small particles may not
be fully interconnected. The more preferred duration is 1 hour or
longer.
[0138] Then, this suspension is brought into contact with a
coagulating solution, whereby said cellulosic small particles are
interconnected.
[0139] Contacting said suspension with said coagulating solution
results in a marked decrease in the mobility of the cellulose or
cellulose derivative molecule so that the intertwining, hydrogen
bonding or the like of the cellulose or cellulose derivative
molecules of the cellulosic small particles may take place.
Moreover, when a binder is concomitantly present, the mobility of
the binder itself is also considerably decreased so that the
interwining and hydrogen bonding or other bonding between the
cellulosic particle and the binder molecule may take place.
[0140] The coagulating solution mentioned above is not particularly
restricted provided that it will deprive fluidity of said alkali
cellulose or alkali cellulose and binder. Thus, for example,
organic solvents such as ethanol, acetone, etc.; solutions of salts
such as calcium salts; solutions of inorganic acids such as
hydrochloric acid, sulfuric acid, phosphoric acid, etc.; organic
acids such as acetic acid etc.; and acidic solutions having pH
values lower than the pH value of said suspension; and pure water
can be mentioned. Those may be used each independently or in a
combination of two or more species.
[0141] The method of contacting said suspension with said
coagulating solution is not particularly restricted but includes,
among others, the method which comprises dispersing said suspension
in said coagulating solution, the method which comprises preparing
droplets of said suspension and bringing the droplets into contact
with said coagulating solution; and the method which comprises
atomizing said coagulating solution into, for example, a mist and
causing the mist to contact said suspension. Particularly in
consideration of the ease of control over the mean particle
diameter of the resulting cellulosic particle body, the method
which comprises preparing droplets of the suspension and letting
the droplets contact the coagulating solution is preferred.
[0142] When the suspension is formed into droplets ahead of time
and contacted with the coagulating solution, the diameter of said
droplets is preferably not greater than 5.times.10.sup.-3m. When
the diameter is greater than 5.times.10.sup.-3 m, the surface
tension is so weak that it is difficult to form the droplets.
[0143] The method of forming said suspension into droplets is not
particularly restricted but includes, among others, the method
which comprises ejecting said suspension from a capillary device
into a gas phase and the method comprising the use of a sprayer.
Particularly because finely divided droplets can be formed, the use
of a sprayer or atomizer is preferred.
[0144] The sprayer mentioned above is not particularly restricted
provided that the suspension can be atomized into droplets
measuring 5.times.10.sup.-3 m or less in diameter. Thus, for
example, a rotary disk sprayer, a pressure nozzle sprayer, and a
twin-fluid nozzle sprayer can be mentioned.
[0145] The rotary disk sprayer mentioned above is based on the
principle that a liquid dripped onto a disk revolving at a high
speed will be centrifugally forced to collide with a gas such as
air and be atomized. The mean diameter of the resulting droplets
can be easily controlled by adjusting the feeding rate of the
liquid and the rotational speed of the rotary disk.
[0146] The pressure nozzle sprayer mentioned above is such that a
liquid under high pressure is ejected from small orifices into an
ambient gas such as air to atomize it. The mean diameter of the
resulting droplets can be easily controlled by adjusting the
feeding rate of the liquid, the pressure applied, and the diameter
of the orifices.
[0147] The twin-fluid nozzle sprayer mentioned above is designed to
atomize a liquid by driving it with a high-pressure with use of
compressed gas, even if a liquid is under low pressure. The mean
diameter of the droplets can be easily controlled by adjusting the
delivery rate of the liquid and the ejection speed of compressed
gas.
[0148] The diameter of droplets of said suspension can be designed
with comparative ease by judicious selection of a suitable one of
the above-mentioned methods.
[0149] The duration of contact between said suspension and
coagulating solution is preferably not less than 1 second. When the
duration is less than 1 second, the cellulosic small particles may
not be sufficiently interconnected. The more preferred duration is
1 minute or longer.
[0150] The cellulosic particle body of the first invention has
interparticle voids or spaces and, therefore, presents with a large
surface area relative to the volume of the particles, so that it
can be used with advantage as a support for immobilization of
microbial cells or enzymes, a carrier or matrix for adsorption of
perfumes and chemicals, and a cosmetic additive, among other uses.
Moreover, because it has high strength, this cellulosic particle
body is amenable to operations at high flow rates. For those uses,
the optimum cellulosic particle body can be selected with reference
to the size, internal structure of the particle body, and the other
factors.
[0151] The above cellulosic particle body may be put to use as it
is or used after modification by, for example, filling an inorganic
or organic substance into said interparticle spaces between the
cellulosic small particles or reacting the particle body with
various substances.
[0152] By the above method of producing said cellulosic particle
body, cellulosic small particles can be easily interconnected and,
moreover, the required voids between the cellulosic small particles
can be easily provided. Furthermore, by judicious selection of the
method of forming droplets of the suspension, the mean particle
diameter of the product cellulosic particle body can be modulated
with comparative ease according to the intended use.
[0153] The second invention is now described in detail.
[0154] The alkaline medium for use in the second invention is not
particularly restricted but includes the various media mentioned
hereinbefore.
[0155] For adjusting its viscosity, said alkaline medium may be
supplemented with glycerin, a water-soluble polymer or the
like.
[0156] The preferred pH of said alkaline medium is not less than 13
(concentration: not less than 0.1 N). The more preferred pH is 14.3
or higher (concentration: not less than 2 N). When the pH is less
than 13, contacting a suspension containing cellulosic small
particles with a coagulating solution results in a dispersion of
discrete cellulosic small particles, thus failing to form the
conglomerate of interconnected particles in some cases.
[0157] The cellulosic small particles for use in this second
invention may be the same cellulosic small particles as those
described in detail hereinbefore for the first invention.
[0158] The cellulosic small particles for use in the second
invention are porous particles with a pore diameter suited for the
intended application. Such porous cellulosic small particles can be
produced by the method of producing the cellulosic particle body
which has been described in detail for the first invention.
[0159] The perfusion type cellulosic particle body of the second
invention can be produced by dispersing said cellulosic small
particles in said alkaline medium and contacting the resulting
suspension with a coagulating solution.
[0160] The duration of dispersing said cellulosic small particles
in said alkaline medium is preferably not less than 1 minute. If it
is less than 1 minute, it may be found difficult to interconnect
said cellulosic small particles sufficiently. The more preferred
duration is not less than 1 hour.
[0161] The suspension concentration of said cellulosic small
particles is preferably 50 to 75 volume %.
[0162] The suspension concentration mentioned above is the
percentage of the total volume of cellulosic small particles in the
suspension relative to the volume of the suspension.
[0163] When the suspending concentration of said cellulosic small
particles is less than 50 volume %, contacting droplets of the
suspension with a coagulating solution yields a fragmentary form of
cellulosic particle body, the strength of which may be low. When
the concentration exceeds 75 volume %, smooth-surfaced droplets can
hardly be obtained and the cellulosic particle body may be a coarse
block. The more preferred range is 60 to 70 volume %.
[0164] The preferred size of said droplets is preferably not
greater than 3.times.10.sup.-3 m in mean diameter. If the mean
diameter exceeds 3.times.10.sup.-3 m, the surface tension will be
so weak that droplets may not be formed.
[0165] The method for forming said suspension into droplets is not
particularly restricted but may for example be the atomizing
technology described in detail above for the first invention.
[0166] The coagulating solution mentioned above is not particularly
restricted but may for example be any of the coagulating solutions
described in detail for the first invention. Among the coagulating
solutions, use of an acidic solution is preferred.
[0167] The acidic solution mentioned above is preferably a solution
with a pH value of 1 or less (concentration: not less than 0.1 N).
The more preferred solution is one having a pH value of -0.3 or
less (concentration: not less than 2 N). When the pH exceeds 1,
contacting a suspension containing cellulosic small particles with
an acidic solution results in a dispersion of discrete cellulosic
small particles and the desired conglomeration may not be easily
achieved.
[0168] The acidic solution mentioned above is not particularly
restricted but includes aqueous solutions of HC1, H.sub.2SO.sub.4,
HNO.sub.3 and H.sub.3P0.sub.4, etc.
[0169] To adjust its viscosity, said acidic solution may be
supplemented with glycerin, a water-soluble polymer or the
like.
[0170] The method of contacting droplets of said suspension with
said coagulating solution is not particularly restricted but
includes, among others, the method which comprises dripping said
droplets into said coagulating solution; the method which comprises
atomizing said coagulating solution, for example into a mist, and
bringing the mist into contact with said droplets.
[0171] The duration of contacting droplets of said suspension with
said coagulating solution is preferably not less than 1 minute. If
it is less than 1 minute, the cellulosic small particles may not be
fully conglomerated. The more preferred duration is not less than 1
hour.
[0172] In the perfusion-type cellulosic particle body of this
invention, the mode of interconnection of said cellulosic small
particles is not necessarily covalent bonding but may be any mode
of interconnection in which the assemblage of individual particles
can be maintained in a stable manner. For example, the
interconnection includes that by intertwining of cellulose
molecules and that by chemical bonding such as hydrogen
bonding.
[0173] The ratio value of the mean particle diameter of said
perfusion type cellulosic particle body is preferably less than 50
relative to the mean diameter of constituent cellulosic small
particles. If the value exceeds 50, the voids between small
particles which serve as flow-through pores will be so small that
the desired perfusion effect is decreased.
[0174] The mean particle diameter mentioned above is selected
according to the intended application. Usually, it is preferably
20.times.10.sup.-6 to 3.times.10.sup.-3 m.
[0175] For the application in which a housing is packed with said
perfusion type cellulosic particle body and a solution
comparatively liable to cause plugging is passed, the mean particle
diameter of said particle body is preferably not less than
100.times.10.sup.-6 m and the flow rate of the solution is
preferably not less than 3.times.10.sup.-4 m/s within the range
which does not cause plugging. When the mean particle diameter is
less than 100.times.10.sup.-6 m, plugging tends to take place and
when the flow rate is less than 3.times.10.sup.-4 m/s, the
perfusion effect is not sufficient so that the efficiency of
operation per unit time will be sacrificed.
[0176] The dried perfusion type cellulosic particle body preferably
has a specific surface area of not less than 2.times.10.sup.4
m.sup.2/kg by the BET method. If the specific surface area is
smaller than 2.times.10.sup.4 m.sup.2/kg, the effective working
area for an application will be too small. The more preferred
specific surface area is not less than 5.times.10.sup.4 m2/kg.
[0177] The above perfusion type cellulosic particle body utilizes
the cellulosic particle body described in detail hereinbefore. This
perfusion type cellulosic particle body comprises a plurality of
cellulosic small particles interconnected so as to have voids
between the constituent particles, in which said voids between
small particles function as flow-through pores while the small
pores in the plurality of interconnected cellulosic small particles
which are open to said through-pores function as sub-pores. The
geometry of said particle body is usually spheroidal or
spherical.
[0178] The perfusion type cellulosic particle body can be used in
many different applications by the judicious selection of a porous
cellulosic small particle and the diameter ratio according to an
application. As such applications, there may be mentioned gel
filtration stationary phase, cellulosic ion exchanger materials,
stationary phase materials for affinity chromatography, adsorbent
matrices for perfumes and chemicals, supports for immobilization of
microbial cells and enzymes, and adsorbent carriers for
purification of body fluids.
[0179] The method of producing the perfusion type cellulosic
particle body of the second invention comprises dispersing porous
cellulosic small particles in an alkaline medium and contacting the
resulting suspension with a coagulating solution to let said
cellulosic small particles be interconnected so as to have voids
between said cellulosic small particles.
[0180] According to the above production method, cellulosic small
particles can be easily interconnected and conglomerated with
provision of voids between particles. Furthermore, since it does
not involve the use of an organic solvent in the course of
production and facilitates washing, the method is very satisfactory
in the prevention of environmental pollutions.
[0181] The third invention is now described in detail.
[0182] The representative monomers for use in the preparation of
the crosslinked polymer particles according to the third invention
may be styrene and its derivatives such as .alpha.-methylstyrene,
chloromethylstyrene, styrenesulfonic acid, etc.; acrylic or
methacrylic acid (briefly, (meth)acrylic acid) and their alkyl
esters, e.g. methyl (meth)acrylate, ethyl (meth)acrylate, butyl
(meth)acrylate, luryl (meth)acrylate, stearyl (meth)acrylate,
sulfopropyl (meth)acrylate, 2-sulfoethyl (meth)acrylate,
hydroxyethyl (meth)acrylate, dimethylaminoethyl (meth)acrylate,
polyethylene glycol (meth)acrylate (the degree of polymerization of
ethylene oxide=2 to 20), hydroxypropyl (meth)acrylate,
polypropylene glycol (meth)acrylate, etc.; vinyl acetate,
vinylpyridine and its quaternization product; vinylsulfonic acids
such as 2-acryloylamino-2-methyl-propanesulfonic acid,
2-acrylamido-2-propanesulf- onic acid,
methacryloyloxypropylsulfonic acid, etc.; vinyl cyanides such as
acrylonitrile, methacrylonitrile, etc.; and vinyl halides such as
vinyl chloride, vinyl bromide, etc., although the above is not an
exhaustive listing. Those monomers can be used each independently
or in a combination of two or more species. However, it is
preferable to use styrene as a monomer unit because it can be
polymerized by any of radical polymerization, anionic
polymerization and cationic polymerization. These monomers can be
polymerized by the known polymerization technology in the presence
of a crosslinking agent to provide crosslinked polymers.
[0183] When the monomer has a salt functional group, hydrochloric
acid, sulfuric acid, phosphoric acid or an organic acid is used as
the counter ion to a cationic group, while an alkali metal,
ammonia, a lower amine, an alkanolamine or the like is used as the
counter ion to an anionic group. Those counter ions can be used
each alone or in a combination of two or more species and, but the
above is not an exhaustive listing.
[0184] The crosslinking agent which can be used in the production
of crosslinked polymer particles includes polyfunctional compounds
having vinyl, hydroxyl, carboxyl, amino, pyridinium, epoxy,
isocyanate, mercapto, aldehyde, acid chloride, acid amide or other
groups, and those crosslinking agents can be used each
independently or in a combination of two or more species. The
crosslinking agent includes but is not limited to aromatic
compounds having two or more vinyl groups, such as divinylbenzene,
divinyltoluene, divinylxylene, divinylnaphthalene, etc. Among those
compounds, divinylbenzene is preferred in view of its high
reactivity to vinyl monomers.
[0185] The crosslinked polymer particles for use in this third
invention are preferably porous. The technology available for the
production of porous crosslinked polymer particles typically
comprises conducting a suspension polymerization reaction in a
mixture comprising a monomer, a crosslinking agent and a solvent
which dissolves the monomer but does not dissolve the polymer
(non-solvent) and removing the non-solvent from the precipitated
polymer for utilizing the ghosts as small pores. The porous
crosslinked polymer particles can be used with advantage as
chromatographic column packings or various adsorbents in the field
of medical care.
[0186] The crosslinked polymer particles mentioned above are
crosslinked polymer particles having particle diameters within the
range of 0.1.times.10.sup.-6 to 10.times.10.sup.-3 m, preferably
1.times.10.sup.-6 to 5.times.10.sup.-3 m, more preferably
10.times.10.sup.-6 to 1.times.10.sup.-3 m. With the crosslinked
polymer particles measuring less than 0.1.times.10 .sup.-6 m in
diameter, the organic binder fills up the voids between the
crosslinked polymer particles of the particle body so that the
objective spherical type body of the invention cannot be obtained.
Moreover, with crosslinked polymer particles measuring over
10.times.10.sup.-3 m in diameter, the great dead load of the
crosslinked polymer particles prevents the particle body from
retaining the conglomerate of crosslinked polymer particles
interconnected by the organic binder in the intact interconnected
condition so that the objective spherical type body of the
invention cannot be obtained.
[0187] The standard deviation of the particle diameter distribution
of said crosslinked polymer particles is not greater than 100% of
the mean particle diameter, preferably not greater than 50%. If the
standard deviation exceeds 100%, comparatively smaller crosslinked
polymer particles find their way into the minute voids or spaces
between the interconnected crosslinked polymer particles to cause a
non-uniform distribution of voids, with the result that the
favorable functions characteristic of the particle body comprising
conglomerate of interconnected particles, which cannot be obtained
with the crosslinked polymer particles as such, are not
expressed.
[0188] The organic binder comprising a non-crosslinked polymer may
be a known polymer and includes not only polymers of the monomers
mentioned above for the production of said crosslinked polymer
particles but also ethylene-vinyl acetate copolymer and its
saponification product or chlorination product, polyethylene and
its chlorination product, polybutadiene, polyisoprene,
styrene-butadiene copolymer, polyvinyl chloride, vinyl
chloride-vinyl acetate copolymer, polyurethane, polyethylene,
polyethylene oxide, polysulfone, polyamide, polyamideimide,
polyimide, cellulose, cellulose acetate, cellulose nitrate,
chitosan and its derivatives, melamine resin, epoxy resin and its
derivatives, among others. Those binders can be used each
independently or in a combination of two or more species and,
moreover, the above is not an exhaustive listing. The mode of
copolymerization may be any of random, block and graft.
[0189] The organic solvent which does not dissolve said crosslinked
polymer particles but dissolves said organic binder comprising a
non-crosslinked polymer includes but is not limited to ketones such
as acetone, methyl ethyl ketone, cyclohexanone, etc.; esters such
as methyl acetate, ethyl acetate, butyl acetate, ethyl carbonate,
etc.; ethers such as diethyl ether; aromatic hydrocarbons such as
toluene, xylene, benzene, chlorobenzene, diethylbenzene,
dodecylbenzene, etc.; heterocyclic compounds such as pyridine;
saturated hydrocarbons such as hexane, heptane, octane, decane,
cyclohexane, etc.; alkyl halides such as methylene chloride,
chloroform, carbon tetrachloride, ethylene chloride, etc.; alcohols
such as isoamyl alcohol, hexyl alcohol, octyl alcohol, etc.; and
other solvents such as 1-nitropropane, dioxane,
N,N-dimethylformamide, diethylthioformamide, dimethyl sulfoxide,
tetramethylene sulfoxide, acetonitrile, hydroxy-acetonitrile,
fumaronitrile, cyanoacetic acid, acetic acid, formic acid,
ethylenecarbonate, propylene carbonate, ethylene oxalate,
.gamma.-butyrolactone, methylene diisocyanate, tetrahydrofuran, and
carbon disulfide. Those solvents can be used each alone or in a
combination of two or more species and the above is not an
exhaustive listing of the solvents which can be used. The amount of
said organic solvent is not particularly restricted but when the
organic solvent is used in an excessive amount, it takes a long
time for the solvent to be evaporated after immersion and,
therefore, it is preferable to use about 1 to 3 volumes of the
organic solvent per volume of the precipitated crosslinked polymer
particles.
[0190] A typical example of production of the spherical type bodies
described above is given below.
[0191] The spherical type bodies can be produced for example by the
following steps I to III.
[0192] Step I
[0193] This is a step in which crosslinked polymer particles
measuring 0.1.times.10.sup.6 to 10.times.10.sup.-3 m in diameter
with a standard deviation of not greater than 100% of the mean
particle diameter are immersed in a solution of an organic binder
comprising a non-crosslinked polymer in an organic solvent which
does not dissolve said crosslinked polymer particles but dissolves
said organic binder.
[0194] Step II
[0195] This is a step following said Step I, in which the above
organic solvent is gradually evaporated off under constant
stirring.
[0196] Step III
[0197] In this step, the crosslinked polymer particles are
interconnected through said organic binder precipitating out on the
surface of said crosslinkd polymer particles with the progressive
reduction in amount of said organic solvent due to evaporation and,
at the same time, the resulting conglomerates of interconnected
particles are subjected to shearing, tumbling and compaction forces
in the course of stirring to provide a substantially spherical type
body.
[0198] By judicious selection of the kinds and amounts of said
crosslinked polymer particles, said organic binder comprising a
non-crosslinked polymer, and said organic solvent which does not
dissolve said crosslinked polymer particles but dissolves said
organic binder comprising a non-crosslinked polymer, there can be
obtained a spherical type body having the desired interparticle
bond strength and/or a spherical type body in which surface of said
crosslinked polymer particles is not covered with the organic
binder but remain exposed to the desired extent.
[0199] The spherical type bodies comprising the above conglomerates
of crosslinked polymer particles according to the invention have
the following characteristics.
[0200] The first of all is the characteristic that the restriction
to the diameter of interconnected constituent crosslinked polymer
particles is moderate compared with the prior technology. Thus,
while the above spherical type body can be constructed by
interconnecting crosslinked polymer particles measuring
0.1.times.10.sup.-6 to 10.times.10.sup.-3 m in diameter with a
standard derivation of not greater than 100% of the mean particle
diameter, there is not a reported case in which crosslinked polymer
particles varying in diameter over such a broad range could ever
been assembled into spherical type bodies according to one and the
same technological principle.
[0201] Secondly, the above spherical type body is fundamentally
different from the conventional spherical type body in that the
surface of the crosslinked polymer particles has an area(s) not
covered with an organic binder. Thus, by selecting the amount of an
organic binder judiciously, it is possible to have the organic
binder distributed exclusively in the voids between the individual
crosslinked polymer particles and to cover the surface of the
crosslinked polymer particle or leave it exposed in the desired
degree. As a result, there can be provided a novel spherical type
body in which the constituent crosslinked polymer particles are
allowed to express their inherent functions sufficiently without
being compromized. Furthermore, when the crosslinked polymer
particles are porous particles, the surface porous structure is not
convered up but remains a part exposed so that the adsorptive
function of the very porous structure is kept intact.
[0202] Thirdly, the above spherical type body is superior to the
conventional spherical type body in the aspect that the crosslinked
polymer particles can be recovered from the spherical type body for
reuse. The conventional spherical type body has to be discarded as
it is after use. In contrast, the spherical type body of the
present invention is such that the organic binder used is soluble
in the same organic solvent as used in the construction of the
spherical type body so that, after use of the spherical type body,
the constituent crosslinked polymer particles can be recovered from
the used spherical type body and reuse.
[0203] Having the above favorable characteristics, the spherical
type body of the invention finds application in a broad variety of
uses. For example, the spherical type body can be used as a column
packing for liquid chromatography and a stationary phase for gel
permeation chromatography in the field of analytical chemistry.
Since the spherical type body comprising interconnected crosslinked
polymer particles according to the present invention contains
interparticle voids, it can be used as the so-called perfusion type
body characterized by flows passing through the internal body.
Thus, compared with fractional purification in a chromatographic
system using the unitary solid crosslinked polymer particles of the
comparable diameter as the stationary phase, the objective solute
can be separated in a shorter time with the spherical type body of
the invention.
[0204] The spherical type body of this invention can also be used
as the adsorbent in various purification systems in the field of
medical care for the purification of body fluids. Here, the
substance having an affinity for the target substance which is an
etiologic agent in a body fluid may be occurring in the crosslinked
polymer particles constituting the spherical type body of the
invention, or a substance having an affinity for the target
substance may be immobilized after the construction of the
spherical type body by interconnecting crosslinked polymer
particles. As a further alternative, the substance having an
affinity for the target substance may be immobilized after the
spherical type body of the invention has been coated with a
functional group-containing substance.
[0205] The etiologic agent mentioned above includes but is not
limited to low-density lipoprotein, endotoxin,
.beta.2-microglobulin, and tumor necrosis factor-.alpha..
[0206] The substance having an affinity for the etiologic target
substance in a body fluid is not restricted provided that it has an
affinity for the target substance but includes, among others,
substances having negative groups such as sulfo, positive groups
such as amino, or hydrophobic groups such as alkyl groups.
[0207] Since the spherical type body of the present invention has a
perfusion type characteristic, the time required for body fluid
purification is expected to be reduced.
[0208] The spherical type body of the invention has particle
diameters within the range of 1.times.10.sup.-6 to
100.times.10.sup.-3 m. Compared with the conventional perfusion
type spherical type bodies measuring 50.times.10.sup.-6 m at most
in diameter, it can be implemented in a remarkably broad particle
size distribution so that it can be utilized for a detailed
investigation of intra-particle flows in the packed column for
chromatography, for instance.
[0209] The fourth invention is now described in detail.
[0210] The adsorbent for purification of body fluids according to
this invention comprises a perfusion type carrier on which a
substance having an affinity for a target substance has been
immobilized.
[0211] The perfusion type carrier mentioned above must have
flow-through pores having sufficiently large diameters.
[0212] In the adsorbent of this invention, in order that the flow
through the carrier particle may be created to reduce the height
equivalent to a theoretical plate explained in connection with the
prior art in this specification, the ratio of the mean particle
diameter of said carrier to the mean diameter of flow-through pores
in said carrier is preferably not greater than 70 and more
preferably not greater than 50.
[0213] In addition, because the adsorbent of this invention is
intended for purification of a body fluid, it is subject to a
certain limit to linear velocity which is specific to the therapy
for purification of the particular body fluid. Thus, when a column
is packed with the perfusion type carrier of this invention and a
solution containing the target substance exclusively is passed at a
linear velocity within the range of 1.times.10.sup.-4 m/s to
10.times.10.sup.-4 m/s, said height equivalent to a theoretical
plate as a carrier characteristic is preferably not greater than
0.5 m, more preferably not greater than 0.1 m.
[0214] The following is a representative method for determination
of the height equivalent to a theoretical plate. A solution
containing the target substance is injected in a pulsating manner
through a column packed with the test carrier to construct an
elution curve. When the theoretical plate number is large as it is
the case with chromatography, the elution curve assumes a Gaussian
distribution and the height equivalent to a theoretical plate
(HETP) can then be calculated by means of the following equation. 3
HETP = L 5.54 ( T r W t ) 2
[0215] wherein L [m] represents a packed column height, Tr [sec]
represents a retention time, and Wt [sec] represents a half-time
width. The retention time means the time at which the peak height
(top) of the elution curve is detected and the half-time width
means the time width corresponding to half of the peak height [F.
Guaise: Optimization of Liquid Chromatography, Kodansha, p.18
(1980)].
[0216] However, unlike in chromatography, the particle diameter of
the adsorbent for purification of body fluids is large and the
length of the housing is limited so that the elution curve of a
target substance as constructed using the housing packed with the
adsorbent for purification of body fluids seldom assumes as
Gaussian distribution. In such cases, the shape of the elution
curve can be used as a qualitative indicator of the adsorbent
performance.
[0217] When the mass transfer is insufficient, i.e. the height
equivalent to a theoretical plate is large and the theoretical
plate number is small, a large proportion of the target substance
cannot be brought into sufficient contact with the carrier but be
eluted along with the flow of the solution introduced into the
housing. Therefore, the peak top position occurs immediately after
emergence of that volume of the solution corresponding to the
interparticle void volume of the carrier and thereafter the target
substance is gradually eluted with the progress of elution
time.
[0218] On the other hand, when the mass transfer is efficient, i.e.
the height equivalent to a theoretical plate is small and the
theoretical plate number is large, the better the mass transfer is,
the greater the frequency of the target substance contacting the
adsorbent is. Therefore, the time during which the target substance
remains in the housing is prolonged and the peak immediately
following completion of emergence of the volume of the solution
corresponding to the interparticle void volume of the adsorbent bed
is small and the peak top position is also shifted backwards.
Moreover, the elution curve becomes closer to a Gaussian curve.
[0219] In the present invention, the geometry of the flow-through
pores in said carrier particles need only be such that a portion of
the flow in the housing may pass through the carrier particles and
the shape and number of pores are not particularly restricted. For
example, the cross-sectional configuration may be circular,
polygonal or amorphous. Moreover, the flow-through channels within
the carrier particles may be linear or curved. In addition, a
plurality of flow-through pores preferably exist and the
flow-through pores may be similar or different in geometry and
extending in parallel or in random directions.
[0220] The carrier may have a construction such that when a body
fluid flows around it, a flow of the body fluid passing through its
interior pores may occur. Moreover, said carrier may be in any of
particulate, slab-like and amorphous forms but is preferably
particulate from the standpoint of the ease of passage and
handling.
[0221] The carrier mentioned above is not particularly restricted
but may for example be a porous carrier having flow-through pores,
a granular carrier manufactured by agglomerating fine particles, a
granular carrier manufactured by assembling fibers, or a granular
carrier processed to have flow-through pores. The fine particles or
fibers for use in the manufacture of said granular carrier are
preferably those having small pores receptive to the target
substance; i.e. having a large contact area for adsorption. The
granular carrier to be processed to have flow-through pores as
mentioned above may also preferably be made of a material having a
multiplicity of small pores receptive to the target substance even
before processed.
[0222] The carrier preferably has a sufficient strength so that it
will not be compacted to undergo deformation of particles to the
extent of interfering with passage of the body fluid.
[0223] The technology for manufacturing said carrier includes the
method which comprises agglomerating particles to provide
flow-through pores, the method which comprises assembling fibers,
the method which comprises processing granules or particles to have
pores, and so on. As to examples of the method for assembling
particles or fibers, there can be mentioned the technique of
effecting assembling during a polymerization reaction for producing
the particles or fibers and the technique which comprises
subjecting only the mutually adjoining surfaces of particles or
fibers, without destroying the structure of particles or fibers, to
a treatment with an organic solvent, heat, an adhesive, an acid, an
alkali, etc. to bond them together. The spaces between the
agglomerated particles or fibers constitute flow-through pores. The
technology for processing particles to have pores includes laser
drilling, solvent leaching and the like.
[0224] The material for said carrier includes native macromolecular
substances such as cellulose, chitin, chitosan, agarose, etc.;
modification products of native substances, such as acylcelluloses,
acylchitins, etc.; synthetic polymers such as polystyrene,
polymethacrylic acid and its derivatives and their copolymers,
polyvinyl alcohol, styrene-divinylbenzene copolymer, etc.; and in
organic materials such as glass, alumina, ceramics, and so on.
[0225] Furthermore, as said carrier, the perfusion type cellulosic
particle body of the second invention or the spherical type bodies
comprising crosslinked polymer particles according to the third
invention can also be used with advantage.
[0226] The target substance mentioned above includes not only the
etiologic agents mentioned by way of example in connection with the
third invention, but also other lipoproteins which may be causative
of atherosclerosis such as very low density lipoproteins;
immunoglobulins (A, D, E, G, M), anti-DNA antibodies,
anti-acetylcholine receptor-antibodies, anti-blood group
antibodies, anti-platelet antibody and other autoantibodies and
antigen-antibody complexes; rheumatoid factors, macrophages,
invasive carcinoma T-cells, and so on.
[0227] The substance having an affinity for said target substance
is not particularly restricted provided that it is capable of
adsorbing the target substance. Although this has been explained in
connection with the third invention, a further discussion seems in
the following. Thus, the affinity between a substance having an
affinity for a target substance and the target substance is
classified into a biological affinity and a physicochemical
affinity. The substance exhibiting an affinity for a target
substance by way of biological interaction includes a substance on
which an antigen has been immobilized, a substance on which an
antibody has been immobilized, a substance which utilizes a
biological interaction such as complement fixation or Fc coupling,
and so on. The substance exhibiting an affinity for a target
substance by way of physical interaction includes a substance which
utilizes an electrostatic interaction, a substance which utilizes a
hydrophobic interaction, and etc. Among them, a substance
exhibiting an affinity for the target substance by way of physical
interaction is preferred in consideration of availability of
materials, stability of the activity during the manufacture,
sterilization, storage and transport of the adsorbent and column,
and the risk for adverse reactions when contacted with blood.
[0228] To describe the substance exhibiting an affinity for the
target substance by way of physical interaction in further detail,
substances having negative groups can be used for adsorbing low
density lipoprotein, for instance. The substances having negative
groups include sulfated polysaccharides such as dextran sulfate,
heparin sulfate, chondroitin sulfate, chondroitin polysulfate,
heparitin sulfate, xylan sulfate, caronin sulfate, cellulose
sulfate, chitin sulfate, chitosan sulfate, pectin sulfate, inulin
sulfate, arginic acid sulfate, glycogen sulfate, polylactose
sulfate, carragenin sulfate, starch sulfate, polyglucose sulfate,
laminaran sulfate, galactan sulfate, levan sulfate, mepesulfate,
etc.; phosphotungstic acid, polysulfated anethol, polyvinyl alcohol
sulfate, polyphosphoric acid, and polyacrylic acid. Among them,
sulfated polysaccharides are particularly effective. Further, as
favorable examples from clinical points of view, heparin and
dextran sulfate can be mentioned.
[0229] The above substances having negative groups are examples of
the substance exhibiting an affinity for a target substance by way
of physical interaction and finding application in the adsorption
of low-density lipoprotein but depending on the specific target
substance, substances having positive and hydrophobic groups and
exhibiting physical interactions can also be used. Moreover, a
plurality of different substances each having an affinity for the
target substance may be immobilized. Aniline may also be mentioned
as an example of said substance having an affinity for the
low-density lipoprotein fraction.
[0230] The technology for immobilizing said substance having an
affinity for the target substance on a carrier or support includes
various known methods such as covalent bonding, ionic bonding,
physical adsorption, embedding, and insolubilization of
precipitation on the surface and those methods can be selectively
used according to the particular substance having an affinity for
the target substance and the kind of carrier material. In
consideration of the loss by release of the substance having an
affinity for the target substance in the sterilization procedure,
the immobilization by covalent bonding is preferred. If necessary,
a spacer may be interposed between the carrier and the substance
having an affinity for the target substance.
[0231] The technology which can be used to render the carrier
reactive to the substance having an affinity for the target
substance in the immobilization of said substance having an
affinity for the target substance on said carrier by covalent
bonding includes the cyanogen halide method, epichlorohydrin
method, bis-epoxide method, and bromoacetyl bromide method, among
others. As the specific groups which can be used in the above
reaction, there can be mentioned amino, carboxyl, hydroxyl, thiol,
acid anhydride, succinylimido, chloro, aldehyde, epoxy, tresyl and
other groups. From the standpoint of stability in heat
sterilization, the epoxy group derived from the epichlorohydrin
method is particularly preferred.
[0232] The preferred adsorbent for purification of body fluids
according to the fourth invention has a mean particle diameter of
not less than 100.times.10.sup.-6 m and a perfusion effect obtained
when a housing is packed with this adsorbent and a solution is
passed at a linear velocity of not less than 3.times.10.sup.-4
m/s.
[0233] When the above adsorbent for purification of a body fluid is
contacted with whole blood, consideration of the possible plugging
with blood corpuscles and the dynamic adsorption performance that
may be obtained suggests that the particle diameter of the
adsorbent is preferably 100.times.10.sup.-6 m to less than
4000.times.10.sup.-6 m, more preferably 100.times.10.sup.-6 m to
less than 600.times.10.sup.-6 m.
[0234] When the body fluid to be treated is whole blood, the
adsorbent must have a sufficiently large particle diameter for
securing pathways for blood corpuscles etc. as compared with the
case when a liquid such as plasma is passed. However, when the
conventional carrier is used, the diffusion distance increases as
the particle diameter is increased, whereby the dynamic
adsorptivity of the adsorbent is decreased. This dynamic
adsorptivity is particularly poor when the conventional adsorbents
of increased particle diameters are used for the treatment of whole
blood.
[0235] On the other hand, in the adsorbent for purification of a
body fluid according to the fourth invention, the carrier produces
a perfusion effect so that the mass transfer is improved as
compared with the conventional carrier in which the mass transfer
of the target substance is solely dependent on diffusion.
Therefore, the adsorbent for purification of a body fluids
according to this invention within the particle diameter range of
100.times.10.sup.-6 m to less than 4000.times.10.sup.-6 m,
preferably 100.times.10.sup.-6 m to less than 600.times.10.sup.-6
m, shows a remarkably improved dynamic adsorptivity when contacted
with whole blood.
[0236] The adsorption apparatus comprising a housing packed with an
adsorbent for purification of a body fluid which is said perfusion
type carrier carrying as immobilized thereon a substance having an
affinity for the target substance is also included in the scope of
the present invention.
[0237] The method of using said adsorption apparatus is similar to
that of using the adsorption apparatus for adsorption of a body
fluid which is conventionally used in a plasma perfusion system or
a direct blood perfusion system. The method can be carried into
practice in the conventional manner, for example with sustained
injection of an anticoagulant into the body fluid circuit for
preventing coagulation of the body fluid and provision of a
pressure probe for sensing the occurrence of circuit plugging.
BEST MODE FOR CARRYING OUT THE INVENTION
[0238] The following examples are intended to illustrate the
present invention in further detail and should by no means be
construed as defining the scope of the invention.
Example 1
[0239] Carboxymethylcellulose (Wako Pure Chemical Ind.) was mixed
with 6 N-sodium hydroxide/water (pH=14.8) to prepare a 5.6 weight %
aqueous carboxymethylcellulose solution. Then, porous cellulose
small particles having a mean diameter of 25.times.10.sup.-6 m
(Chisso Corporation) were mixed with the above
carboxymethylcellulose-containing aqueous sodium hydroxide solution
(suspension concentration 65 vol. %, the binder fraction 2.0 wt. %)
for 5 hours under constant stirring. Then, using a micropipet with
a tip diameter of 0.5.times.10.sup.-3 m, the suspension was dripped
into contact with 99.5% ethanol solution, whereby a substantially
spherical cellulosic particle body was obtained. The diameter of
the particle body was about 0.6.times.10.sup.-3 to
1.times.10.sup.-3 m. When this spherical cellulosic particle body
was rinsed with pure water and shaken in pure water, the particle
body retained its original shape. No deformation of the particle
body occurred, either, when the above cellulosic particle body was
held between the thumb and the index finger and rolled over a
distance of about 5.times.10.sup.3 m for 5 reciprocations by
rubbing the fingers against each other in the lengthwise direction.
The pH value was calculated by means of the equation pH=-log.sub.10
[H.sup.+] assuming the degree of dissociation of the aqueous
solution of sodium hydroxide and an aqueous solution of HCl=1 and
[H.sup.+].times.[OH.sup.-]=10.sup.-14. The same applies to the pH
values given hereinafter.
[0240] Pure water was substituted for the liquid within the above
cellulosic particle body obtained and after ethanol substitution,
substitution with 2-methyl-2-propanol was further carried out. The
particle body was then lyophilized using a freeze-dryer (Eiko Eng.
Co., Ltd.) and after vapor deposition of gold, the lyophilizate was
examined with a scanning electron microscope (Topcon). As shown in
FIG. 3, the resulting cellulosic particle body was substantially
spherical. Furthermore, voids were observed between the
interconnected cellulosic small particles as shown in FIGS. 4 and
5. Moreover, as can be seen in FIG. 6, the pores which had existed
in the constituent porous cellulosic small particles were still
observed even after interconnection.
Example 2
[0241] A porous cellulosic small particle having a mean particle
diameter of 25.times.10.sup.-6 m (Chisso Corporation) were mixed
with 6 N-sodium hydroxide/H.sub.2O (pH=14.8) (suspending
concentration 62 vol. %; the binder fraction 0.0 wt. %) for 5 hours
with constant stirring. Then, using a micropipet with a tip
diameter of 0.5.times.10.sup.-3 m, the suspension was dripped into
contact with 6N-HCl/H.sub.2O (pH=-0.8), whereby a substantially
spherical cellulosic particle body was obtained. The diameter of
this particle body was about 1.times.10.sup.-3 m.
[0242] The cellulosic particle body obtainable by this production
technology, wherein a binder is not used, did not lose its shape
even when it was washed with pure water and shaken in pure water.
However, this particle body failed to retain its shape when it was
held between the thumb and the index finger and rolled over a
distance of about 1.times.10.sup.-3 m by rubbing the fingers
against each other in their lengthwise direction.
Example 3
[0243] Carboxymethylcellulose was mixed with 6N-sodium
hydroxide/H.sub.2O (pH=14.8) to prepare a 5.6 wt. % of
carboxymethylcellulose solution. Then, a porous cellulose small
particle having a mean particle diameter of 25.times.10.sup.-6 m
(Chisso Corporation) was contacted with the above solution of
carboxymethylcellulose in sodium hydroxide/H.sub.2O (suspension
concentration 63 vol. %, the binder fraction 2.0 wt. %) for 5 hours
under constant stirring. Then, using a twin-fluid nozzle means
(having an inner and an outer nozzle in concentric relation),
compressed nitrogen gas was ejected from the outer nozzle while the
above suspension was dispensed in a mist form from the inner
nozzle. The delivery rate of nitrogen gas was 3.3.times.10.sup.-4
m.sup.3/s and the dispensing rate of the suspension was
1.1.times.10.sup.-7 m3/s. The diameter of the inner nozzle of said
twin-fluid nozzle means was 2.6.times.10.sup.-3 m and the diameter
of the outer nozzle was 4.4.times.10.sup.-3 m. The delivery head
was 4 m. Using 99.5% ethanol as a coagulation bath, droplets of
said suspension were mixed with the bath, whereby the cellulosic
particle body of the invention was formed in the coagulation bath.
The mean diameter of the particle body was about 2.times.10.sup.-4
m. When the cellulosic particle body thus obtained was rinsed with
pure water and shaken in pure water, each particle body retained
its original shape.
[0244] Substitution of pure water for the liquid within the
cellulosic particle body thus obtained was followed by ethanol
substitution and, then, substitution with 2-methyl-2-propanol was
carried out. The particle body was then lyophilized with a freeze
dryer (Eiko Eng. Co., Ltd.) and after vapor deposition of gold, the
particle body was examined using a scanning electron microscope
(Topcon). The cellulosic particle body obtained as above was
substantially spherical and voids were observed between the
interconnected cellulosic small particles. Furthermore, the pores
which had been available in the constituent porous cellulosic small
particles could be still observed even after interconnection.
Example 4
[0245] Sodium alginate (Wako Pure Chemical Ind.) was mixed with
6N-sodium hydroxide/H.sub.2O (pH=14.8) to prepare a 3.6 wt. %
sodium alginate solution. A porous cellulose small particle having
a mean particle diameter of 25.times.10.sup.-6 m (Chisso
Corporation) was contacted with the above sodium alginate solution
in NaOH/H.sub.2O (suspension concentration 65 vol. %, the binder
fraction 1.3 wt. %) for 6 hours under constant stirring. Then,
using a micropipet having a tip diameter of 0.5.times.10.sup.-3 m,
droplets of the above suspension were brought into contact with
6N-calcium chloride/H.sub.2O, whereupon a substantially spherical
cellulosic particle body was obtained. The diameter of the particle
body was about 0.7.times.10.sup.-3 m. This cellulosic particle body
retained its shape even when rinsed with pure water and shaken in
pure water. The particle body fully retained its shape even when it
was held between the ventral sides of the thumb and index finger
and rolled over a distance of about 5.times.10.sup.-3 m for at
least 5 reciprocations by rubbing the fingers against each other in
their lengthwise direction.
[0246] Following substitution of pure water for the liquid within
the cellulosic particle body thus obtained, ethanol substitution
and, then, substitution with 2-methyl-2-propanol were carried out.
It was then lyophilized with a freeze-dryer (Eiko Eng. Co., Ltd.)
and, after vapor deposition of gold, examined using a scanning
electron microscope (Topcon). As can be seen in FIG. 7, which is a
sectional view of the cellulosic particle body, the particle body
was substantially spherical. It can also been in FIGS. 8 and 9 that
the particle body contained voids between the interconnected
constituent cellulosic small particles. Furthermore, as shown in
FIG. 10, the pores which had been available within the constituent
cellulosic small particles were still observed even after
interconnection.
Example 5
[0247] J Sodium Silicate No. 3 (a concentrated aqueous solution of
sodium oxide and silicon dioxide (water glass), Nippon Kagaku
Kogyo) was mixed with 6N-sodium hydroxide/H.sub.2O (pH=14.8) to
prepare a 30.6 wt. % solution of J Sodium Silicate No. 3. Then, a
porous cellulose small particle having a mean particle diameter of
25.times.10.sup.-6 m (Chisso Corporation) was contacted with the
above solution of J Sodium Silicate No. 3 in sodium hydroxide/H20
(suspension concentration 62 vol. %, the binder fraction 11.6 wt.
%) for 6 hours under constant stirring. Then, using a micropipet
having a tip diameter of 0. 5.times.10.sup.-3 m, the above
suspension was dripped into contact with 6N-calcium
chloride/H.sub.2O, whereupon a substantially spherical cellulosic
particle body was obtained. The diameter of each particle body was
about 0.5.times.10.sup.-3 m. This cellulosic particle body retained
its shape fully when rinsed with pure water and shaken in pure
water. Moreover, the particle body fully retained its shape even
when it was held between the ventral sides of the thumb and index
finger and rolled over a distance of about 5.times.10.sup.-3 m for
at least 5 reciprocations by rubbing the fingers against each other
in their lengthwise direction.
[0248] Following substitution of pure water for the liquid within
the cellulosic particle body obtained above, ethanol substitution
and substitution with 2-methyl-2-propanol were serially carried
out. It was then lyophilized with a freeze-dryer (Eiko Eng. Co.,
Ltd.) and, after vapor deposition of gold, examined using a
scanning electron microscope (Topcon). As a result, the cellulosic
particle body was found to be substantially spherical. There also
were observed voids between the interconnected cellulosic small
particles and, even after interconnection, the pores available in
the constituent porous cellulosic small particles were still
observed.
Example 6
[0249] A porous cellulose small particle having a mean particle
diameter of 20.times.10.sup.-6 m (Chisso Corporation) was suspended
in 6N-sodium hydroxide/H.sub.2O (pH=14.8) at a final concentration
of 70 vol. %. The suspension was thoroughly agitated with a stirrer
and using a capillary pipet having a tip diameter of
0.7.times.10.sup.-3 m, the above suspension was dripped into
contact with 5N-HCl/H.sub.2O (pH=-0.7), whereupon a cellulosic
particle body was obtained.
[0250] The diameter of each particle body was about
2.times.10.sup.-3 m. The cellulosic particle body thus obtained was
rinsed with pure water.
[0251] Following substitution of ethanol for the liquid within the
above cellulosic particle body, substitution with
2-methyl-2-propanol was carried out. The particle body was then
lyophilized using a freeze-dryer (Eiko Eng. Co. Ltd.) and, after
vapor deposition of gold, the lyophilizate was examined with a
scanning electron microscope (Topcon). As a result, this cellulosic
particle body was found to be substantially spherical as shown in
FIG. 11. In addition, as is evident in FIG. 13, there were voids
between the interconnected cellulosic small particles. Furthermore,
the pores available in the constituent porous cellulosic small
particles were still observed even after interconnection as shown
in FIG. 14.
Comparative Example 1
[0252] A porous cellulosic small particle having a mean particle
diameter of 20.times.10.sup.-6 m was suspended in pure water at a
final concentration of 70 vol. %. The suspension was thoroughly
agitated with a stirrer and using a capillary pipet having a tip
diameter of 0.7.times.10.sup.-3 m, the suspension was dripped into
contact with 5N-HCl/H.sub.2O (pH=-0.7), whereupon the cellulose
particles were simply dispersed.
Comparative Example 2
[0253] A porous cellulosic small particle having a mean particle
diameter of 20.times.10.sup.-6 m (Chisso Corporation) was suspended
in 6N-sodium hydroxide/H.sub.2o (pH=14.8) at a final concentration
of 70 vol. %. After thorough agitation with a stirrer, the
suspension was dripped from a capillary pipet with a tip diameter
of 0.7.times.10.sup.-3 m into contact with pure water, whereupon
disk-shaped masses of cellulose were obtained. Upon shaking, the
disks collapsed to give a dispersion of discrete cellulose
particles.
Comparative Example 3
[0254] A porous cellulose small particle having a mean particle
diameter of 20.times.10.sup.-6 m (Chisso Corporation) was suspended
in 6N-sodium hydroxide/H.sub.2O (pH=14.8) at a final concentration
of 40 vol. %. The suspension was thoroughly agitated with a stirrer
and using a capillary pipet with a tip diameter of
0.7.times.10.sup.-3 m, droplets of the suspension were mixed with
5N-HCl/H.sub.2O (pH=-0.7), whereupon fragment-like masses of
cellulose were obtained. When shaken, those masses collapsed,
giving a dispersion of discrete cellulose particles.
Comparative Example 4
[0255] A porous cellulose small particle having a mean particle
diameter of 20.times.10.sup.-6 m (Chisso Corporation) was suspended
in 6N-sodium hydroxide/H.sub.2O (pH=14.8) at a final concentration
of 80 vol. %. The suspension was thoroughly agitated with a stirrer
and using a capillary pipet with a tip diameter of
0.7.times.10.sup.-3 m, the suspension was dripped into contact with
5N-HC1/H.sub.2O (pH=-0.7). As a result, smooth-surfaced droplets
could not be formed but the resulting cellulosic masses were
massive form.
Example 7
[0256] A porous cellulose small particle with a mean particle
diameter of 20.times.10.sup.-6 m (Chisso Corporation) was suspended
in 6N-sodium hydroxide/H.sub.2O (pH=14.8) at a final concentration
of 70 vol. % and the resulting suspension was agitated well with a
stirrer. Using a twin-fluid nozzle means (having an inner and an
outer nozzle in concentric relation), compressed nitrogen gas was
ejected from the outer nozzle while the above suspension was
dispensed from the inner nozzle. The nitrogen ejection pressure was
5.times.10.sup.3 kg/m.sup.2 and the suspension dispersing speed was
5.19.times.10.sup.--4 m.sup.3/S. The diameter of the inner nozzle
of the above twin-fluid nozzle means was 2.6.times.10.sup.-3 m and
the diameter of the outer nozzle was 4.4.times.10.sup.-3 m. The
delivery head was 4 m. As a result, the objective cellulosic
particle body was obtained in an acidic solution. The mean particle
body diameter was about 200.times.10.sup.-6 m.
[0257] Following substitution of ethanol for the liquid within the
above cellulosic particle body, substitution with
2-methyl-2-propanol was carried out. It was then lyophilized with a
freeze-dryer (Eiko Eng. Co., Ltd.) and, after vapor deposition of
gold, the particle body was examined using a scanning electron
microscope (Topcon). As shown in FIG. 15, this cellulosic particle
body was spherical. As can be seen in FIG. 16, voids were available
between the interconnected cellulosic small particles. It can also
be seen in FIG. 17 that the pores originally available in the
constituent cellulose particles were still evident after
interconnection.
Comparative Example 5
[0258] A column (in. dia. 0.01 m, 0.05 m long) was packed with a
porous cellulosic small particle (mean particle diameter
179.times.10.sup.-6 m) (Chisso Corporation) which is of the same
structure (e.g. pore diameter) as the cellulose particles used in
Examples 6 and 7 and Comparative Examples 1 to 4 but different in
mean particle diameter. Then, physiological saline at 23.2.degree.C
(Otsuka Pharmaceutical Co.) was passed through the column at a
linear velocity of about 5.times.10.sup.-4 m/s and
100.times.10.sup.-9 m.sup.3 of a 5-fold dilution of a low-density
lipoprotein reagent (L-2139, SIGMA) in physiological saline was
injected in a pulsating manner. The time course of change in the
concentration of low-density lipoprotein was monitored with an
absorptiometer (ATTO) at the wavelength of 280 nm. As shown in FIG.
18, the peak top was confirmed to occur in the position immediately
following the beginning of elution. The cellulosic particles used
had pores receptive to the low-density lipoprotein. Therefore, the
above characteristics of the elution curve were not attributable to
the absence of pores through which low-density lipoprotein could
enter the cellulosic particle body but rather attributable to the
fact that because the particle size of the particle body was large,
the mass transfer distance was long and, therefore, the low-density
lipoprotein could not migrate sufficiently within the cellulosic
particle body but was eluted out from the column exit together with
the flow down in the interstices of the cellulosic packing.
Example 8
[0259] A column (0.01 m in. dia., 0.05 m long) was packed with the
particle body obtained in Example 7 (the mean diameter ca
200.times.10.sup.-6 m, the ratio of the mean diameter of the
cellulosic particle body to the mean diameter of cellulosic small
particles=10). Physiological saline (Otsuka Pharmaceutical Co.) at
23.2.degree. C. was passed at a linear velocity of about
5.times.10.sup.-4 m/s and 100.times.10.sup.-9 m.sup.3 of a 5-fold
dilution of a low-density lipoprotein reagent (L-2139, SIGMA) in
physiological saline was injected in a pulsating manner. The time
course of change in the concentration of low-density lipoprotein
was monitored with an absorptiometer (ATTO) at the wavelength of
280 nm. As shown in FIG. 19, the peak top position was delayed as
compared with Comparative Example 5. The particle body used in this
example was a perfusion type particle body (particle body diameter
ca 200.times.10.sup.-6 m) comprising cellulose particles (particle
diameter 20.times.10.sup.-6 m) having pores similar to those of the
cellulose small particle (particle diameter 179.times.10.sup.-6 m)
used in Comparative Example 5. Therefore, the above elution curve
was obtained because, even though the particle diameter of the
particle body was large, its perfusion structure insured a faster
mass transfer for low-density lipoprotein within the particle body
so that the low-density lipoprotein could migrate easily within the
particle body.
Example 9
[0260] As the crosslinked polymer particles, the
divinylbenzene-crosslinke- d polystyrene carrier HP21 from
Mitsubishi Chemical Co. (Synthetic adsorbent Diaion.TM. HP21) was
used. This HP21 was dried at room temperature and classified
through standard sieves, and a fraction measuring
350.times.10.sup.-6 to 425.times.10.sup.-6 m with a standard
deviation of 29% of the mean particle diameter was used. As the
organic binder, Styron.TM. (Asahi Kasei Polystyrene, Grade G8102,
Color No. K27, particle size 71) was used. Methyl ethyl ketone was
used as the organic solvent which does not dissolve crosslinked
polymer particles but dissolves the organic binder.
[0261] The above HP21 in an amount of 16.6 g was put in a 100 ml
beaker measuring 5 cm in diameter and stirred using a mixer (EYELA
D. C. STIRRER DOL-RT, Type DCL-2RT; Tokyo Rika Kikai K. K.) with a
3-blade impeller (4.9 cm dia.) inserted into the beaker in contact
with its bottom. The number of revolutions was 50 rpm. To crush and
trim the coarse lumps formed in the above stirring granulation,
stirring at 500 rpm was further carried out for 1 minute. The
rotational speed of the impeller was controlled with a slidac
(Yamabishi Electric Co., Ltd., BS-130-100MC) connected to said
stirring mixer.
[0262] Then, under constant stirring, 31 ml of a solution of
Styron.TM. in methyl ethyl ketone (13 mg/ml) was added. While the
stirring was continued, methyl ethyl ketone was removed by means of
draft suction and a dryer (cold air). The yield of the spherical
type bodies thus obtained was about 5 weight %. The spherical type
bodies were so tough that they did not collapse under finger
pressure.
[0263] FIG. 20 is a light microphotograph [SMZ-10 (Nikon)] showing
the particulate structure of the spherical type body. The spherical
type body was immobilized on a sample station with an
electroconductive tape and subjected to gold/palladium vapor
deposition. A scanning electron microphotograph of the spherical
type body surface [ABT-32 (Topcon)] is shown in FIG. 21. It will be
apparent from FIG. 21 that the surface of the spherical type body
showed two areas, namely the organic binder area and the HP21
surface area. Thus, the presence of the exposed surface areas of
crosslinked polymer particles which were not covered with the
organic binder could be confirmed. Moreover, on the section of the
spherical type body, voids were observed between crosslinked
polymer particles and, in addition, the presence of the organic
binder in the interconnecting parts of the adjoining crosslinked
polymer particles could be confirmed. The above findings indicated
that on both the surface and the section, voids existed between the
crosslinked polymer particles.
Example 10
[0264] Carboxymethylcellulose (Wako Pure Chemical Ind. Co.) was
mixed with 6N-NaOH/H.sub.2O to prepare a 2.9 wt. %
carboxymethylcellulose solution. A porous cellulose small particle
with a mean particle diameter of 25.times.10.sup.-6 m (Chisso
Corporation) was suspended in the above aqueous
carboxymethylcellulose-NaOH solution (the percentage of the total
volume of cellulose particles relative to the volume of the
suspension=65 vol. %; the percentage of the weight of
carboxymethylcellulose relative to the weight of the suspension=1.0
wt. %) for 5 hours under constant stirring. Then, using a
twin-fluid nozzle means (having an inner and an outer nozzle in
concentric relation), compressed nitrogen gas was ejected from the
outer nozzle while the above suspension was dispensed from the
inner nozzle into a coagulation bath of 99.5% ethanol to trap
therein. The nitrogen gas ejection speed was 3.3.times.10.sup.-4
m.sup.3/s and the suspension dispensing speed was 1.2.times.10
.sup.-7 m.sup.3/s. The diameter of the inner nozzle of the
twin-fluid nozzle means was 2.6.times.10.sup.-3 m, while the
diameter of the outer nozzle was 4.4.times.10.sup.-3 m. The
discharging head was 4 m. The carrier thus obtained was rinsed with
pure water and wet-classified through 180.times.10.sup.-6 m and
355.times.10.sup.-6 m sieves to provide a carrier having a mean
particle diameter of 256.times.10.sup.-6 m.
[0265] After substitution of ethanol for the liquid within the
carrier, substitution with 2-methyl-2-propanol was carried out and
the carrier was then lyophilized (Eiko Eng. Co., Ltd.). After vapor
deposition of gold, the lyophilized carrier was examined using a
scanning electron microscope (Topcon). As shown in FIGS. 22 and 24,
the surface and cross-section of the carrier presented with voids
(flow-through pores) between the interconnected cellulose
particles. Moreover, as shown in FIGS. 23 and 25, small pores
(adsorptive pores) could be observed on both the surface and
cross-section of the carrier. The carrier thus obtained had
flow-through pores and small spores available for adsorption, thus
having a structure such that internal flows occur when there is a
flow around it.
Reference Example 1
[0266] Determination of the Upper-Limit Linear Velocity
[0267] A column having an internal diameter of 10.times.10.sup.-3 m
and a length of 110.times.10.sup.-3 m was packed with the carrier
obtained in Example 10 (mean particle diameter 256.times.10.sup.-6
m), and fresh bovine blood supplemented with citric acid as an
anticoagulant and maintained at 37.degree. C. was passed through
the column. The blood was introduced at a constant linear velocity
and when the pressure loss became steady, a change was made to a
higher linear velocity. In this manner, the upper-limit linear
velocity at which the pressure loss because constant was
determined. As a result, the upper-limit linear velocity was found
to be 7.32.times.10.sup.-4 m/s.
Comparative Reference Example 1
[0268] Determination of the Upper-Limit Linear Velocity
[0269] Using the commercial carrier POROS.TM. (Perceptive
Biosystems; mean particle diameter ca 50.times.10.sup.-6 m), fresh
bovine blood was passed and the upper-limit linear velocity at
which the pressure loss could be kept constant was determined as in
Reference Example 1. As a result, even at the initial linear
velocity level of 0. 75.times.10.sup.-4 m/s, the pressure loss did
not become steady but continued to rise and ultimately the packed
column was plugged with the blood. The experiment was
discontinued.
Comparative Reference Example 2
[0270] Determination of the Upper-Limit Linear Velocity
[0271] Using a porous cellulose carrier (Chisso Corporation; mean
particle diameter 220.times.10.sup.-6 m) which was similar to the
cellulose particles used in Example 10 (mean diameter
25.times.10.sup.-6 m) in pore geometry but larger in mean particle
diameter, fresh bovine blood was passed and the upper-limit linear
velocity at which the pressure loss could be kept steady was
determined as in Reference Example 1. As a result, the upper-limit
linear velocity was found to be 5.78.times.10.sup.-4 m/s.
[0272] As can be understood from Comparative Reference Example 1,
POROS.TM. as a commercial perfusion type carrier was small in
particle diameter so that direct blood perfusion was difficult. On
the other hand, the carrier obtained in Example 10 had a higher
upper-limit linear velocity at which the pressure loss could be
maintained as can be seen from Reference Example 1. When blood was
passed through the column conventionally used in the purification
of body fluids (400.times.10.sup.-6 m.sup.3 in volume and
110.times.10.sup.-3 m long) at a linear velocity of
7.32.times.10.sup.-4 m/s, the flow rate was 2.66.times.10.sup.-6
m.sup.3/s (159 ml/min), which falls within the therapeutic range
(0.833.times.10.sup.-6 to 3.33.times.10.sup.-6 m.sup.3/s (50 to 200
ml/min).
Reference Example 2
[0273] Determination of the Elution Curve
[0274] A column (0.01 m in. dia., 0.20 m long) was packed with the
carrier obtained in Example 10 (mean particle diameter ca
256.times.10.sup.-6 m the ratio of the mean diameter of the carrier
to the mean diameter of cellulose particles=10). Then,
physiological saline (Otsuka Pharmaceutical Co.) at 23.2.degree. C.
was passed at a linear velocity of about 4.6.times.10.sup.-4 m/s
and 100.times.10.sup.-9 m of a 5-fold dilution of a low-density
lipoprotein reagent (SIGMA, L2139) in physiological saline was
injected in a pulsating manner. The time course of change in the
concentration of low-density lipoprotein in the eluate was
monitored with an absorptiometer (ATTO) at the wavelength of 280
nm. The resulting elution curve is shown in FIG. 26. The "sita" on
the abscissa represents the percentage of the amount of elution
relative to the internal void volume of the carrier and "E" on the
ordinate represents the solute concentration obtained by
transformation so that the total integral area of the elution curve
would be equal to 1. FIG. 26 shows two peaks. The first peak top is
situated immediately following completion of emergence of the
solution corresponding to the internal void volume of the carrier
(sita =1) and this peak height was small.
[0275] When albumin (mol. wt. 6.6.times.10.sup.4) was injected
under the same conditions as in Reference Example 2, the peak top
was situated at "sita"=ca 1.8. Since peaks of an elution curve in
the absence of adsorption are such that a sbstance having a larger
molecular weight emerges earlier, the above result indicates that
the first peak corresponds to low-density lipoprotein which has a
large molecular weight (mol. wt. 300.times.10.sup.4 to
500.times.10.sup.4).
Comparative Reference Example 3
[0276] Determination of the Elution Curve
[0277] Using the carrier of Comparative Reference Example 2 (Chisso
Corporation; mean particle diameter 220.times.10.sup.-6 m), the
elution curve of low-density lipoprotein was determined under
conditions similar to those used in Reference Example 2. The
elution curve thus determined is shown in FIG. 27. The first peak
top occurred immediately following completion of emergence of the
volume of the solution corresponding to the interparticle void
volume of the carrier and its peak height was large.
[0278] With reference to the results in Reference Example 2 and
Comparative Reference Example 2, the shape of the elution curve in
Reference Example 2 featured a smaller height of the first peak and
trailing as a whole as compared with the curve obtained in
Comparative Reference Example 3. It is, therefore, clear that the
carrier of Example 10 (mean particle diameter 256.times.10.sup.-6
m) is superior to the carrier of Comparative Reference Example 6 3
(mean particle body diameter 220.times.10.sup.-6 m) with a better
mass transfer characteristic.
[0279] It is supposed that despite its having a larger mean
particle diameter than the carrier of Comparative Reference Example
3, the carrier of Example 10 produces a perfusion effect resulting
from the presence of flow-through pores, thus contributing to a
faster mass transfer of low-density lipoprotein within the
carrier.
[0280] Referring to the elution curves of Reference Example 2 and
Comparative Reference Example 3, the occurrence of the peak of
low-density lipoprotein immediately following completion of
emergence of the volume of the solution corresponding to the
interparticle void volume is not attributable to the absence of
pores providing access to the interior of the carrier but
attributable to the fact that because of the larger particle size
of the carrier, the distance of mass transfer is larger so that the
low-density lipoprotein does not come into sufficient contact with
the carrier particles but emerges out of the column along with the
flow down in the interparticle passages of the column packing. The
cellulosic small particles constituting the carrier used in
Reference Example 2 (mean particle diameter 25.times.10.sup.-6 m)
and the carrier of Comparative Reference Example 3 (mean particle
diameter 220.times.10.sup.-6 m) are similar to each other in pore
geometry and receptive to low-density lipoprotein. The fact that
low-density lipoprotein may enter into those pores has been
confirmed by the successful adsorption of low-density lipoprotein
using the carrier of Example 10 in Examples 11 and 12.
Example 11
[0281] The carrier obtained in Example 10 was reacted with
epichlorohydrin at 45.degree. C. for 2 hours and, then, reacted
with dextran sulfate at 40.degree. C. for 24 hours to provide an
adsorbent with dextran sulfate immobilized thereon.
[0282] The above adsorbent was added to fresh human serum in a
ratio of 1 volume, as sediment, to 6 volumes of the serum and the
mixture was shaken at 37.degree. C. for 10 hours. The concentration
of the supernatant was then measured to calculate the adsorption
rate.
Adsorption rate (%)=(concentration of initial liquid-concentration
of supernatant)/concentration of initial liquid.times.100
[0283] The adsorption rates of low-density lipoprotein-cholesterol,
high-density lipoprotein-cholesterol, and albumin were 51%, 0% and
0%, respectively, indicating that the adsorbent has a specific
affinity for low-density lipoprotein.
Example 12
[0284] The carrier obtained in Example 10 was reacted with
epichlorohydrin at 45.degree. C. for 2 hours and, then, reacted
with aniline at 50C for 6 hours to provide an adsorbent carrying
aniline immobilized thereon.
[0285] Using the above adsorbent, the adsorption rates were
determined under the same conditions as in Example 11. The
adsorption rates of low-density lipoprotein-cholesterol,
high-density lipoprotein-cholesterol- , and albumin were 55%, 0%
and 0%, respectively, indicating the affinity of the adsorbent for
low-density lipoprotein.
[0286] It is clear from Examples 11 and 12 that the carrier of
Example 10 on which a substance having an affinity for a target
substance was immobilized can be used as an adsorbent.
INDUSTRIAL APPLICABILITY
[0287] The cellulosic particle body according to the first
invention and the perfusion type cellulosic particle body according
to the second invention, the structures of which have been
described hereinbefore, provide for a comparatively large freedom
of design in the aspect of particle size according to various
applications and, depending on the size and internal structure, can
be used with advantage in various applications such as gel
filtration stationary phases, cellulosic ion exchanger substrates,
carriers for affinity chromatography, carriers for adsorption of
perfumes and chemicals, supports for immobilization of microbial
cells and enzymes, and adsorbent carriers for purification of body
fluids, among others. The method of producing the cellulosic
particle body of the first invention and the method of producing
the perfusion type cellulosic particle body of the second
invention, both of which have been described hereinbefore, can be
used to easily produce said cellulosic particle body of the first
invention and said perfusion type cellulosic particle body of the
second invention.
[0288] Furthermore, according to the third invention, crosslinked
polymer particles can be interconnected via an organic binder to
provide with ease a novel spherical type body with small
restriction to the diameter of crosslinked polymer particles to be
interconnected and structural characteristics that the surfaces of
said particles have areas not covered with the organic binder but
remaining exposed.
[0289] The spherical type body according to the third invention,
which has the above-mentioned structural characteristics, permits
effective expression of the properties of crosslinked polymer
particles without compromise of their inherent function and
therefore finds application as adsorbents in the field of medical
care, for example as chromatographic column packings and in body
fluid purification systems. The spherical type body of this
invention can be reused by dissolving out the organic binder to
regenerate the crosslinked polymer particles.
[0290] In addition, the adsorbent for purification of body fluids
according to the fourth invention, the construction of which has
been described hereinbefore, has a high degree of dynamic
adsorptivity so that it can be expected to reduce the therapeutic
treatment time and, hence, improve the patient's quality of
life.
* * * * *